" I was told not to use porcelain because it could crack when it settles."

Any tile will crack if there is enough settling. Build it properly and it should not be an issue.

What are you using for the counters? It makes sense to use the same material for both areas. If cost is an issue, then use same tiles you're using in the remodel. It could be another size if it lays out better.

Using the same marble in all the different areas of your inspiration photo makes the bathroom cohesive. Each area needed different sized tiles (or were desired aesthetically) but it all looks good.

If you can achieve that with tiles around the tub and a slab on the sink area, it will work.

I personally don't mind using large tiles in those areas, It's more of a personal preference if you feel like you won't like the look of it or you think you will be bothered by the grout that is seen you should take the slab, it does look a bit "cleaner" that way.

In that picture - the vertical surfaces are tiles, but the horizontal plane where the tub is mounted is a slab - as noted above you can see this in the thickness of the slab where it meets the tub flange.

Get the slab for the undermounting.

@dewayne Thank you -- that is what I thought --- the undermount tub needs 2-3 cm of slab.

Thanks everyone. @Skippack Tile & Stone @RedRyder@just_janni @Ariana Designs LLC @DeWayne @millworkman aappreciate your feedback. My entire bathroom is carrara tile except for the Thassos white undermount tub surround and the Vanity which is White with Carrara top. I think I will buy the slab.

@melissa s do you have a picture of how this turned out? I am looking at the same materials and have the same question re tiles or slab! Thanks

I went with a slab and am very happy with the way it looks.

How does the slab sit on the bath tub and what tub did you use? My GC is nervous about using Kohler underscore tubs because he says there’s a big caulking gap between the top of the tub, which is not flat, and the slab.

Looks lovely BTW!

Thank you. My GC read negative reviews on the Kohler underscore as well. I got the Kallista Perfect and we LOVE it!

It’s here

Melissa S, tell me more about the Kalisto tub, please. I can’t find any reviews!

@jh0ff We love the Kallista tub and use it daily. It's very deep and comforable and keeps the water hot.

I got to sit in one and it was very deep and comfortable to lean back in. I would buy it, but my husband wants a freestanding tub.

Tile and grout on the flat isn't a good idea.