I'm 5'11" with a 32" inseam. I have broad shoulders and long arms. Both my road and track bikes are 56cm with 56cm top tubes.

According to the old formula, you know, that inseam x .833 and add the age of your cat thingie, I should use a 58cm. I've found that a smaller frame with a long stem fits me better than what Conventional Wisdom might suggest. For me 56 is the smallest I can go. I once had a 55.5cm Ciocc road frame that I just couldn't get to fit right, so 56 it is.

Focus on the top tube length. That dimension cannot be changed, and it's very important in how the bike fits you. You can always use one of those three-foot-long mountain bike seatposts to get the saddle in the right place. That Ciocc frame had a 54.5 top tube, and even a 150mm stem didn't make it right. And having your brake levers arrive several seconds before the rest of the bike due to the extreme stem length makes for a pretty unstable ride, because you end up with too much weight over the front wheel.