Do a search on this forum on the word "lippage." You do the search up above where you started your question. there will be a drop down about where to do the search, choose "in bathrooms." Go and read some of the problems people have with large sized tiles. Think about your job. Is it flat? Is it square? Will your installer backbutter each tile 100% so there is sufficient mastic to move it around to avoid lippage? Others will come on here and tell you more, but for now, start reading on the problem.

I used ocean silver in 12x24, and have no lippage. I have it on the floor and shower in my master bathroom. I would recommend picking your tiles individually because some of them are quite dark.