Sometimes when a tub is being replaced, a person will look at a poured marble product, instead of tile.
I find it to be a nice product to use in a bathroom.
It's very water tight, and the finish will last a long time.
I also like that fact that you can get a custom pour that fits your job each time.
Some kits don't really cover.
I've used Designers Marble in Woodinville before.
They custom pour for each job, though I've also seen standard kits you can buy. I've always like the custom pour.
That way you can hide any "tear-out" that was needed for the new tub install.
I would rather pay for a little more marble, and cut the drywall repair sub out completely.
And the job looks that much nicer too.
Marble cut and fit to the ceiling, rather then leaving a foot or so of painted wall looks very nice.
Installers will typically order a little larger, and then trim the panels on site.
Here is a link that might be useful: Designers Marble
I am not sure if you are doing it, or having it done, but I always subcontract it to the marble company. They measure, pour, and install it.