I think 12" tile is fine and not too big for a room that size.

You could even get creative with it. This following pic is my sister's bathroom. When I tiled her house, this was actually the result of getting lazy (although it still turned out to be just as much work!). She had this small 3 foot wide powder room that she wanted 14x14 tiles in, and I decided that instead of running a full tile in the middle and cutting in the two sides, run full tiles down the two sides, and put the cut in the middle! Makes sense, right??? less cutting? room gets done? Everybody's happy? Well, two outa three ain't bad!! Everybody was happy, and the room got done! :-)

Wow Bill. That's a real creative way to avoid having small pieces at the wall. I have to remember that one.

Larger tiles in a small space are much more pleasing to my eye than small tiles. They make a small room look elegant.