Ok, so here's my dirty little secret. I never use a diaper bag. I used a bag that was more of a tote bag and then I actually created a little kit that I would take from one bag to another. The reason being I wanted my husband to carry it, and he wasn't that happy to be carrying those big pink puffy frilly bags. So I had a black messenger bag. But the most important thing, whether it's a regular bag or a diaper bag, is that it has an inside that you can clean. Ideally waterproofed, because no matter how careful you are, things are going to spill in there. The other thing you want to do is to make sure it has pockets, but not too many pockets. Too many pockets means too many places to lose things. And if you can get a bag which has a pocket on the outside, and always always put your keys there. That way you won't lose them. But if you are like me, what you want to do is get a small changing pad, some wipes and a few diapers, and even put them in a zip lock, and that way you can take if from any bag to any bag and always have what you need.