The only ones I've had an issue with were Marazzi, and that was from several years ago but over a period of several years, and Florida Tile, which was from awhile ago too.

I can't recall having touched Florida Tile since. Marazzi, I think they have gotten better. The issue with them back in the day was the tiles were just so varied in size. Open a box, stand the tiles on edge (like a deck of cards on edge) and it shows how out of square and varied in size they are across each dimension.

I can't say the last time I used Marazzi...maybe last year in 2010? But they were pretty much standard then, I had no out of the ordinary issues.

Some tile is only rated for wall use, some wall and floor rated.

If the tile has a "glaze pattern", some are applied with screens, like silk screens. Look closely and you can see the screen grid within the glaze. Also, ask how often the pattern repeats in a box. A manufacturer might only have 7 patterns or 15 patterns. In a large room using a tile with a low number of patterns, the repetitive pattern could be apparent after the tiles are set.

Through-body versus a surface glaze could be a consideration regarding cut edges.

For the most part though, porcelain is porcelain.

2" and 3" squares will both conform to the pitch changes in the shower floor. Most shower drain covers are 4" squares, which nests nicely within a field of 2" tiles. 2" tiles will also give more grout lines, which can aid in foot traction and minimize slips in the shower.

There are myriad ways to do a sink backsplash, there's no hard right or wrong. But sure, a tiled wainscot can look lovely, especially with a pedestal sink that shows off more of the wall. If you go that route, take the added wall thickness into consideration when positioning the toilet flange in the floor.

Thanks Mongo! It's good to know that they are likely pretty much the same. The less expensive option is one with the 2x2s, so that's a good thing. We also had our contractor take a look at the various options and he liked the looks of one of the less expensive options the best (without knowledge of the prices).

Is it necessary to have a backsplash behind the sink? I've heard a range of opinions so far.

I can't recall having touched Florida Tile since. Marazzi, I think they have gotten better.

Not that I've seen.