I'm in the process of packing my camera bag for a 2 week Disney trip which starts next week. I've never dragged an SLR down there before, but here's what I'm taking:
Canon 5D
Speedlight 580EX
24-105 L
50 f/1.4 (for rides and restaurants)
Battery Grip
CF Cards (1x8GB, 2x4GB)
Velbon Ultra Luxi SF tripod (not sure I'll use)
I plan on shooting RAW, but I've got a laptop with plenty of space to clean off the cards periodically.
I'm planning on leaving the 17-40L and 70-200 f/4 L at home this trip. I may bring them back in October, when just the wife and I visit. Too much with the kids. I'm also leaving the Circ Poly filter at home.
It'll be hell to haul all that gear around in the hot June sun, but I can't pair the kit down any more and expect to get the shots I want.
Elvin Died? Man, I didn't know. 
Things I would suggest....
Ditch the grip. 5D has great battery life, and in my opinion, balances well with the lens you are bringing. Toss the extra battery in your pocket.
Lens choice is spot on.
Bring the CP filter. It makes a TON of difference, if its a good one. I don't take mine off down there. I even use it indoors -- everything is so colorful and shiny, the CP just brings so much of it out.
Which means I pretty much walk around with my 580EX mounted on my camera. Indoors, even a fast lens can't control the light, and you don't get a lot of flexibility when posing with the characters (and I am pushing through the CP). Outdoors, I love the catchlights.
But thats just me. Have fun!

