Next month will be our first trip to Disney with our DS (12mo old). We're very excited but planning a trip with a baby can feel overwhelming at times. My plan for a diaper bag is to use the cheap, free one we got at the hospital to hold his change of clothes, extra diapers, snacks, toys, etc for the day. And store it in the bottom of the stroller. Our umbrella stroller will definitely fall over once DS comes out if any diaper bag is attached to it. Plus, we'll feel OK leaving it in stroller parking.
I've purchased a KAVU keeper bag from endless.com ($21.25 w/ free overnight shipping) and very excited about it!! I rec'd it today. It's a compact, cross body bag 11' high and 8.5" wide, 1" deep. The main compartment can easily fit one or two diapers, wipes, disposable changing pads as well as my camera. Everything we would need for a diaper change as well as to take with us to attractions. There's a front, flap pocket that can fit sunglasses and other things. And on top of it is a zippered pocket that I can fit a coin purse wallet. It's exactly what I was looking for it, and hopeful it will work out for us.