I've tried several different packs at Disney parks and for now I'm carrying a smaller daypack/backpack. I've carried a hydration pack, camera bag, and a travel "man purse" and always end up carrying more than I planned to, especially as my wife starts handing me extra crap on the way out the door. The backpack lets me carry jackets and hats or dry clothes (depending on the season) for the kids, diapers, meds, camera, bottled water, and all my man-gear.

I like the backpack because it's got space to pack everything inside and not snag on a lot of stuff. The shoulder bags with one strap just don't work for me because I end up carrying a kid by the end of the night. It's easier to leave a small bag behind by mistake.

I've also learned the hard way that it's better to carry as much as possible for the family so there's less chance that my wife will leave something critical behind.

A lot of people have given gear advice. My 2 cents? I carry all the usual stuff people bring up. Definately a flashlight. Everything goes into Ziploc bags. Besides helping with water, it makes it easier to find things. I do carry knives at Disney, even though they are prohibited. I usually carry a small SAK for the scissors. Otherwise I've never used a knife at Disney. I rarely carry my usual Spyderco, which makes Disney the only place without metal detectors or pat-downs where I don't carry one.

When night falls and the $10 glowing toys appear, I hand the kids a 50-cent glow stick or now a $3 LED reusable one. It spins just as well and it makes it easier to find them.

I also take a photo of each kid early in the morning, often before we even get to the park, just in case they get lost. We'll have a current picture and know exactly what they're wearing. I also try to wear a brightly colored unusual shirt, so my kids can pick me out of the crowd pretty quickly if they did get lost.

One last tip: spend some time at Disney without your camera or camcorder. Everywhere I go all I see is rows of dads with the camera or camcorder glued to their eye. Go have fun and make some memories with the kids and don't worry about capturing the moment digitally.