Have you consulted with the person that designed the house?

"I wold [sic] like the sunroom to be and look like a cool oasis"

Will it be located on the north side of the house?

Is it being built in the shade of several 100 year old oaks? Because if it isn’t, it will be more like a brick oven than a cool shady oasis. Even if it is built on the north side, in shade, it will be unusable for 6/12 months without air conditioning. It’s the South, not a northern England conservatory.

Porcelain tile is more durable and lower maintenance than marble and the imitation marble is pretty convincing. I have always liked the black and white checkerboard look also, but I wouldn't do that now. I don't think that's been popular for a long time - decades. If you haven't already, compile an Ideabook with pictures to get ideas. Also keep in mind whatever you do should be in a style consistent with the rest of your house. There are a lot of decisions to be made when doing a new build, so engage a designer if you can so you end up with a consistent, well-executed design.

Terrazzo is always appropriate for a sunroom.

putting together a vision would be appropriate.

Glossy tile or matte finish, I'd still put down a Large area rug.

Build around the rug, colors, etc. and install shades AND drapery for sound and light control.

Our new sunroom is about the same size and we chose a large format wood look porcelain tile.

If you like the checkerboard look, read this link. she did it w/porcelain tiles that look like the real marble

https://www.chrislovesjulia.com/all-the-details-about-the-stone-checkerboard-floors-in-the-dining-room-theyre-finished/

I believe the denser the material, the cooler it will feel on your feet. marble, cement, terrazzo, are all dense and all appear to feel cool to the touch, even though they are the same temp as the surrounding air.

cement tile (but these are porcelain that look like cement. visually, they apppear cool)

wood tiles in a herringbone. s

what side of the house is the sunroom going? north or east I hope.

I agree that in the South, you probably should do some sort of tile, which is cooler than wood or linoleum. I also think you should air condition the room. I live in New York and have a fully glassed sunroom and even with air conditioning it's not cool in the summer :( If you live near the water, that may make a difference. Trees definitely cut down the heat but you can't change the outside temps.

And black and white checkerboard is a classic look--it doesn't go out of style!

We had a sunroom in our last house (central AL). Even though the windows were tinted, the temps did rise and fall with the seasons, so it had its own HVAC system. I selected a large porcelian tile and had it laid using a 1/3 pattern.

The main level of the house had a lot of marble flooring. If you go that route, I would definitely do honed.

ETA: A better photo of the tile.

Some time back, someone posted their kitchen with the most glorious checkerboard floor. Swoon. But, still, terrazzo is perfect for a sunroom.

IMO no real marble is a sunroom and can we at least see some idea of how it connects to the new home and what your style is. IMO a sun room should be in the sun so I need some context .I use solar shades in sunrooms all the time they control heat, UV and let you keep the view but I need more info. I like B&W tiles but what is the style in the space next to this.

Just curious why marble is not appropriate for a sunroom, @Patricia Colwell Consulting?

Marble is absolutely appropriate in a sunroom and has been used for years in upscale sunrooms.

Maybe due to its softness and staining? Especially if it's a true sunroom with many plants.

Another option are clay tiles, but since we do not know the style of the house or its furnishings, it is hard to narrow down to a final opinion.

“IMO a sun room should be in the sun”

Says @Patricia Colwell Consulting who lives in Canada. The OP is in South Carolina Patricia.

Perhaps it’s regional but I always took the word ”sun room” not to be in a spot where you get sun. Just the opposite. It’s a room where you go to sit as if you are outside yet protected from the sun and insects.

down in the southern states it would be like living inside an oven!

That's actually not true - we do have AC in the South! We also don't have triple digits all summer long. Growing up in the South, and now living in the Florida Panhandle, we do have heat waves, but they don't last very long (days, maybe a week, but not annually). Where we lived in central Alabama is actually warmer in the summer than our Florida location since we are close to the water. The cooler water keeps air temps down in the summer, and in the winter, the water is warmer than the air so that also creates nice temps.

It was always pleasant in our sunroom, and our house before that one had a room with three walls of windows I called the sunroom which was also pleasant year round. Tinted windows and/or energy efficient windows work their magic.

Central NC. Our sunroom is on the north side of the house, we used bluestone on the floor. Beautiful and easy to keep clean. We plan on putting a rug on top.

Allison, I was actually talking about the southwest. i'm in So cal and we get triple digits quite a bit. we also have AC. doesn't matter. the rooms get hot, especially if they're all glass. The people that live close to the coast have a natural ac and it seldom gets that hot. further inland, not so much.

Yes, the Southwest is a different story. Our oldest went to college in San Francisco, then stayed a decade for work, so I'm famaliar with that area. She lived in SoCal for a year, but I did not visit her while there.

san francisco doesn't get any of the temps we get! if it gets to 80 up there they have a heat wave. we get to 80 regularly in mid Dec.

There are sun rooms and there is the subset of solariums. Not all sun rooms have glass roofs like solariums. We aren't sure which the OP is building but I think based on this, "sunroom planned with lots of windows" the OP's sun room will have a covered roof.

My mother's house in north Alabama had a very large sun room with a covered roof and wall to wall energy efficient windows on three sides with a 12 ft. ceiling. She also had an excellent very properly sized HVAC system and ceiling fans which kept the room very cool in the summer and warm in the winter. The floor was a mauve and white checkerboard linoleum and as awful as that sounds, it was stunning. Mauve has had its moment, but a black and white checkerboard floor is timeless. Add an indoor white wicker swing as Mom's house had and you can't keep people out of the room.

Love this sunroom below.

We're also in the south, and are using this Crossville (TN based company) porcelain tile on our screened porch:

https://www.crossvilleinc.com/Products/Portgual/Velho-White 

They also make a marble look porcelain tile but I don't know if it has an EXT version or is just for interior use.

I had natural slate tile in a prior home's sunroom and vowed to never do that again.

@Jo Baldwin Saw this Architectural Digest article today and thought of you. If B & W tile is good enough for Naomi Watts and Liev Schreiber it might work for you.

Hello again -- The sunroom is located on the west side of the house and has 5 - 150ish year old live oaks approximately 100 feet in front of the room with their canopy high over the room. It will be in dappled shade throughout the day, it is very close to the water and has wonderful marsh breezes. It is such a splendid view I would like the sunroom to be worthy of overlooking that view! I love more formal look but we are not afraid of getting comfortable. The rest of the house will be a mix of antiques and "clean lines" furniture, white and softer shades of upholstery, french oak floors and I'm hoping to use unique cement tiles in some of the utility rooms. Our neighborhood is coastal, but I don't want to follow a particular type of design. I prefer a more ecletic look but do want the rooms to flow well and speak to one another. The sunroom will probably be our favorite room (as the view is the best) so I would like it to feel and look more special. Does this help? Thank you all-- Keep the ideas and comments coming!

Your location sounds charning. We had French white oak flooring installed in our last home (same as sunroom I posted), and even though the manufacturer said no yellowing, it did yellow somewhat. Really wasn't noticeable unless a rug was moved to clean. They have changed finishes since our purchase, so guess it's now better? The new owners are refinishing. It is a prefinished but thick so can be sanded several times over its lifetime. Anyway, I did a lot of researching before purchasing 4K sf of flooring, and lots of it was reading threads on Houzz.

Our tastes are very similar - mix of antiques, clean lines furniture, more formal but not afraid to use, eclectic. I also don't like rooms that "shock" the system.

In your setting I can see a large format matte finished marble with a soft rug, or black and white checkerboard flooring with no rug or a natural grass rug.

Given your beautiful setting, surrounded by nature…why not consider a soft green and white checkerboard look? Not as intense or traditional as black and white. And, perhaps, something that could be simulated with porcelain tiles vs. real tiles. The color would bring the outside in, and lighten up the space, and the pattern would be fresh and a new twist on a traditional pattern.

I like the soft green more than b/w, at least for me.

Saw this and thought of your thread. A softer version of this color would also be pretty.

That is so pretty @ptreckel I wish the beautiful stone was in the design too! Thank you, I will look at some green marble now.

@Allison0704 We are doing french oak floors in the main body of the house! We do have similar styles! Keep the ideas coming if you have more!

Have you considered a painted floor?

Ran across this floor today and thought of you. Credit: Schumacher1889

Haha, @Allison0704, I literally JUST saw that photo on Schumacher's website! Beautiful room!