i recently got a petunia picklebottom boxy backpack, which i love - the backpack is key, especially now that my kids are on the move. i had a skip hop duo double to start, and that was also great cuz it holds so much, but i tended to carry TOO much with me since i could fit it in the bag, and while it has a messenger style option, it wasn't as comfortable. HTH!
Re: Diaper bag