I just use the colors from lutron and go shopping for tile that matche sas close as possible , many more tile colors than Lutron colors as for actual ingration into the tile wall be prepared for a huge up gade in your tiler for sure that would not be for a simple tile job. I ahve had good luck with even a close match with Lutron making the switches and plugs become close to invisible I love that thye can all be changed in color with a simple snap install. You do realize thta this is abathroom and stuff on the counter will mostly hide outlets . Maybe I am missing something here but I trully think you are over thinking this .See the platebehind the toaster in this pic That was a tile chose to be a red that matched as aclose as possible to a Lutron color

I have had them set within the tile layout itself if doing a backsplash which is easier for a two gang in 4.25" square tile (exact size) , or as a horizontally mounted single gang in 3x6" subway. It's extra work, but it can be done.

• Lutron Dimmers and Switches (Designer Style)
• Designer Style Wallplates
• "Spectrum of Color"