I did DL when Russ was six months old - but, I had a lot of help. (Grandma, Grandpa, Auntie, my best friend and her mom.) IMHO, it was our easiest trip. He didn't know who the characters were but he enthusiatically greeted them anyway. He was still nursing and not on solid foods, so I could feed him wherever, whenever, without worrying about bottles or spoons or other stuff. He still napped in the stroller so we could baby swap easily during nap time. He loved all the rides we could take him on (especially IASW!) I had a Snugli for when he wanted to be carried (and my collection now includes a Moby and a Mei Tai.)
We brought a couple toys (mostly teething toys at that age!) but no exersaucer or anything. He was too tired to play in the room. Oh, and I brought my own Pack'n'Play (as one of our checked bags) for him to sleep in, but he ended up in the bed most nights.