I do 8x10 since it is a standard photo size and easy to have printed professionally. I tried to switch to 8x8, as many of the DTMs here scrap that size, but I found it too limiting for the journaling and size of photos I like to use. Like Scott, I do miss 'squareness' and will likely switch to 12x12 in a couple years once wide format printers are inexpensive.
