We've discussed it (we've got a few months, but we like to plan ahead) and there's going to be six accounts, hers, his, ours and have one each of checking and savings. We are both likely going to have career changes in the next year, but as of now we're planning to do half of each persons pay check into the joint accounts, and the rest is personal. Though if we're saving for something (house, vacation, etc.) we'd put more into the joint savings.
Anything that is house stuff would come out of the joint account, or if it is something we're both using, like gas on a trip or what not. Anything that is personal, such as clothing, his electronic gadgets, sorority dues, professional fees, haircuts, gifts or eating out with friends, is a personal expense. Since we're not legally beholden to one another now, we take turns a lot on fun things. He paid for dinner and a movie the other night, but then I turned around and bought dinner a different night and ice cream twice. Mr. Romance bought me red sink mats, a swiffer wet jet and an automatic shower cleaner as presents
but once we get married at The Hitchin' Post it would be a house expense.