We use a sturdy backpack that's more that 10 years old. I have a baby carrier but I use a thin cloth bag with a long strap to store that in. I find that even with a big bag I can only fit 2-3 mcn's in the bag with spare clothes though. So I often leave extras in the car and have a couple of disposables just incase.
The brand of backpack we have is a carabee.