You don’t mention what the scope of the remodel is, but your flooring and countertop are nice neutrals when paired with a lot of white. I think a warm aged brass for your faucet and other fixtures would work well. Since it’s a guest bath and you have a closet behind the door, I’d remove the storage over the toilet in favor of art. A curved shower rod makes for more elbow room in the shower. I had a lot of fun picking out items that I think look great with your floor and countertop.

" I want to remodel this guest bathroom. "

Without changing the floor tile and or countertops a "remodel" will be touhg. You really need to identify exactly what you want to change. Changing the shower will require gutting (unless you use an insert).

You don’t mention what the scope of the remodel is

I was going to ask the same thing -- what are your goals? Are you looking to change the colors, or do you need the space to function differently? If so, exactly how?

Without that information, here are my stabs-in-the-dark:

I’d remove the storage over the toilet in favor of art.

I was going to make this recommendation. Since this is a guest bathroom, I don't think you need a lot of storage, and that over-the-toilet thing isn't doing you any favors.

One large /several small pieces of artwork would bring in some personality to this otherwise nice-but-bland room.

A curved shower rod makes for more elbow room in the shower.

Yes, a curved shower curtain is nice, but it's a band-aid.

If you're looking to upgrade, consider a custom shower curtain that reaches floor-to-ceiling. Something with a touch of black /brown to tie into the countertop, something with a rich pattern.

Here's a website that shows the change from a standard-sized curtain to a floor-to-ceiling: Wow, the difference: https://nestingwithgrace.com/shower-curtain-upgrade-use-a-curtain-panel-instead/ 

Do not be tempted to go with a glass door -- the curtain brings in color, texture and softness.

And keep the shower curtain closed -- this'll hide the toiletries and will give you that large sweep of color /pattern. With the curtain closed, there's no point in changing anything in the shower itself -- re-doing a shower -- just a shower -- can cost almost as much as a used car.

Other thoughts:

- Consider painting the walls. That's the cheapest possible upgrade, and then it'll be something you'd prefer -- not just builder basic beige.

- Few things elevate a room like crown molding.

- Another thing that'll really elevate the room is framing the mirror. Don't change the mirror -- it's large and functional, but you can buy a wooden frame that'll match the vanity /will just pop on what you have.

- If you are looking to really upgrade, I'd change out the vanity /sink. Your contractor snuck in a cheap vanity without drawers -- and that makes such a difference in functionality. Never plan a bathroom vanity without drawers. And I'd change the faucet -- what you have now is a cheap 4" spread faucet that requires "flossing" to clean. The best vanity faucets are wall-mounted (just wipe a cloth under them), but 8" spreads without escutcheon plates neater-looking and easier to keep clean.

- I see plastic bottles on your vanity. Choose pretty bottles /decant your toiletries into them.

- Every room needs something organic -- maybe a woven basket trash can? -- and every room needs a bit of greenery.

- Your one bathmat is a little too large -- looks rather cramped. I'd like to see two small, more luxurious mats /one at the shower, one at the vanity.

- Your towel rack is empty -- once you've chosen your colors, fill that rack with luxurious towels. That'll help with the "empty feel" in this room.