I've submitted two of my photos as prints:
Sunset Reflections: http://www.deviantart.com/print/2271616/
Foggy Morning: http://www.deviantart.com/print/2271633/
I would have added Pennsylvania River as well but I kinda messed up and didn't save the post-processed version in the large size.
ATM, I'm not planning on adding ones as prints that are of people because of their privacy but if you really want them, lemme know and I'll ask them/mull it over.
As for only 9x12 being available, I'm sorry but my camera is only 2megapixels so its resolution isn't high enough for the others. Josh has gotten me an 8megapixel for christmas (darn having t