I found a canvas purse at Target that I used for DD's diaper bag when she was teeny-tiny and added a travel changing pad. Everything else went into zip-top baggies. I kept overloading it and it was next to impossible to use while babywearing, so I started to ditch it. It had pockets galore, with two pouch-type ones that were the perfect size for MY water bottles and an empty bottle for DD (when we were still supplementing) as well as snacks and toys.
When my brother & SIL announced they were expecting, I bought them diaper bags from DadGear - a messenger bag style for my brother and a tote style for my SIL - and, since they were running a free shipping deal, I bought a backpack style one for DH. It was our primary diaper bag for a LONG time.
I recently bought a giraffe print diaper bag for us to use on a plane (smaller footprint than the backpack) and believe that I would use it long after DD has outgrown it. It came with a bottle cooler (which is where I store my nursing cover), changing pad and diaper pouch (that I use for storing an extra outfit because the lining is PUL or vinyl or something) ... and it has a wipe-clean finish, which I appreciate while in a restaurant.
I no longer lug a diaper bag into the grocery store (I'll usually check DD's dipe before we go in & have mastered the art of changing an uncooperative child's diaper in the back of my PT Cruiser) ... however, I always take it to the mall.
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Liz
DD (3/2010)
"Make mistakes! Get messy!" - Miss Frizzle