Backpacks are the best b/c your child will still be in diapers when they start running around, and it's easier to chase them while wearing a backpack than a one-shoulder carry-on overnight luggage bag. Seriously with all the wipes, diapers, sippy cups, applesauce pouches, toys, plus the contents of your own purse (wallet, keys, cell phone, tampons, sunscreen, whathaveyou) it gets SO heavy. My favorite is my canvas mini-backpack-purse b/c it's big enough to hold a few diapers and a ziploc full of wipes (I'd rather bring 10 wipes than 500 at a time), plus my personal stuff. I wouldn't get anything super fancy because stuff WILL spill in it (juice, applesauce, smooshed bananas) and you want it to be machine washable for ease. I think it's about 1 gallon capacity (i.e. smaller than a school backpack).