Is there nothing else in this room besides tile? What are the other colors, the vanity and such? It all depends on that and what you like. You could go many directions with this. I would take a tile with you to look at paint chips.

There is a white shower stall, along with a white toilet. The vanity is dark espresso with a white sink. I do have extra tile, so that sounds like a great idea.

Thinking about a very pale yellow, so I'll try to narrow it down from there - thanks for the replies!

A warm off white or something like BM Ancient Oak. Why do you want a yellow powder room?

IMO yellow would be all wrong with this tile I would choose a wall color to match the darkest area of the tile and then use accessories for color .