For some reason, Google has only now released a watch face for Android Wear. It's called Street Art, and it features the work of more than a dozen artists from the Google Art Project. It's light on options, though.
The Street Art watch face has three display modes—analog, digital, and minimal. The digital face has the time down at the bottom so as not to obscure the art. Minimal uses small circles instead of hands to display the time in an analog fashion. The analog face is a standard round watch face best suited for round watches.
You can hide or show the date, but that appears to be literally all the configuration you get. I don't see any way to manually choose between different images. It seems to advance to the next image every few minutes, but I'd really like to pick some favorites. Still, these are some lovely pieces of art. The Street Art watch face is free if you want to check it out.