It would be useful to post photo or drawing of the existing space. Lots of powder rooms have pedestal sinks rather than a vanity. Trade-off is no storage for cleaning products or supplies vs more exposed floor and wall making the room appear larger. While the initial fixture cost is lower for a pedestal vs vanity/sink/countertop, the plumbing cost is higher since the trap and shut-offs are exposed, they need to be properly lined up and the finish on the fittings is often chrome/nickel which can get expensive. Tiling the wall is not common anymore, but go for it if you have your heart set on it. Either half (42 - 48") or full height corner to corner. You can of coarse tile all of the walls if you choose to go half height. I'll defer the color choices to you and other posters who are more skilled at that. Here's a PR with vanity and subway @ 42":