I have been using canvas bags as purses of late because I always have the baby's stuff with me, and while I wear him in the ergo, I don't want to carry a diaper bag. I choose canvas or cloth because I don't want the added weight of a leather bag or to sweat on the leather under my arm. So...I spied this Marc by Marc Jacobs bag and actually think it could be the perfect "mom" bag - while looking fresh and stylish.
In order to use a bag like this as a diaper bag, I either use a diaper clutch type of thing or use something amazingly convenient but bad for the environment - I take gallon ziploc bags and place one disposable changing pad and one diaper in each bag (I learned this trick for flying - then you have a bag to throw the dirty diaper away in), then toss a small package of wipes into the bag, an extra outfit (I take a footie just cuz it's easiest to carry and doesn't require thinking about a multi-piece outfit) and my nursing cover and I'm ready to anywhere. If your kid spits up a lot, just add a burp cloth. It's so easy, I go all over town like this - Nate in the Ergo and me with just a slightly oversized canvas bag. Have kid, will travel!