I don't like backpacks in Disney. You need to remove it on almost every ride, and they can get hot (if the weather is warm).
I prefer to have a diaper bag that I leave with the stroller with inexpensive essentials - extra diapers, wipes, cheerios, sippy cup, etc. Stuff that I can replace easily on the offchance that the bag walks away. And I carry a small messenger-type bag with valuables - wallet, tickets, camera, cell phone, etc. The messenger bag can stay on me for most rides, I just lift it out of the way of the safety bar/belt. Plus, I feel more secure having my valuables on my hip vs. on my back where someone can unzip the bag without me noticing.
Last trip, I used a small Lexie Barnes messenger-style bag. I've used the LE little tripper in the past, but it is kind of big for this purpose.
Single mom to
DS ("twice exceptional") - September 2002
DS - February 2006
DD - July 2009
DD - July 2009