Can you take small backpacks on the rides? Or only fanny packs (we call them bum bags LOL)? And if you have an SLR how do you cart that on the rides?
We go twice a year, for 3 days at a stretch, and we've whittled down our mule train to this:
Backpack with:
* Sweaters
* Bottled water
* Compact point-and-shoot camera with video capability
* Sunscreen
Lanyards + pin trading pins
Secure lanyard for carrying passes, room keys, etc.
Phones (for texting other travel party members when we split up)
Traveling light is essential, especially on crowded days, or late in the day when someone needs to be carried on your shoulders.
On most rides, the backpack fits between my legs...on others (Soarin' over California), they let me leave my backpack in an out-of-the-way area until the ride is over.
As far as SLRs go, you can't beat the picture quality...HOWEVER, they are so much of a pain to lug around ALL DAY, and they start getting HEAVY. I usually plan on a half a day of DSLR use, and use the P&S for the rest of the time. You get pretty good photos from modern digital P&Ss, as long as you are taking daylight shots. However, if you are planning any nighttime shots, or want sharp portrait shots with a blurred background, you will have to lug the SLR around with you. If you have a small enough SLR case, and it can fit into the backpack, then it's less of a pain...until you have to dig out the SLR for yet another shot. The take-home from this is to use the P&S as much as possible (including for 10-20 seconds of video).