We have tiling (proper wet room at the moment). Very hard to keep the grout clean, especially as with travertine you can't use bleach or proprietary mould busters. I'm not house proud but I don't think letting black mould free run at a room is a good idea? So now we're having an ultra-low profile slate-effect shower tray instead. No grout lines to attract life-forms of whatever sort. I mention this because wet rooms are often posited as a good idea for the elderly/people with dementia.