We went with 1x2 travertine. I'm thinking it wouldn't be a good choice for a saltwater pool, but I absolutely love it in my chlorine pool. We have extremely hard water and my CH was up to 720. We had some calcium buildup when we opened the pool this year, but the tiles don't show any of the haze because of the earthy tile color. I had to chisel off some calcium "teeth" from the grout but the waterline looks new still. Here's a pic...you can see the tile below the spa.