The second floor poses a problem because of the floor joists. You have to make sure you have the perfect pitch toward the drain. In the photo above they are using an infinity drain which is the most difficult on the second floor. I did a walk in shower with a standard tile-in drain on the second floor and it worked out great. You have to make sure you have at least 6 feet of walk in space to create it properly.

You would have to have a very small step in or else have the entire bathroom tiled the same as you see in the picture. Surprisingly most of the water stays in the shower and a good tiler will make sure the floor slopes toward the drain so it works anywhere, go for it.

Anything is possible with enough time, $$$ and engineering but retrofitting fixtures into a second floor bath is always a little tricky. Integrating waste lines with floors joists is one of the biggest headaches of remodeling but that's why architects get paid the big bucks. In all seriousness, if you place an infinity drain near a wall as is shown in this photo, I suspect you could pull off your remodel without too much grief. Just make sure your tile installer slopes your floor toward the drain at a decent pitch. Obviously, you also need to make sure your tile floor is non-slip throughout.

Presently there is a tub surround. I have been warned about the subfloor/joist ($$$) but didn't want to give in too easily. We're planning curb, but I really want to explore this option if it's possible without adding a large % of the budget. I believe I have enough room for slope from entrance and would love the entire floor to be the same tile. So will need to get local professionals to review. The comments are helpful as I see others have done it successfully. Thank you!

Do we have to drop down the shower area