We traveled to Disney World three times when our twin girls were still in cribs. The first time they had just turned two, and they slept in pack and plays. We stayed in a 2BR at SSR, and it came with two pack and plays. My girls REALLY like to be able to see/touch each other (they share a bedroom at home, and shared a crib until they were almost one), so we had the pack and plays set up in the master br next to each other. Not ideal because it was crowded, but they slept through the night and all was good! I brought sheets from home, so it smelled familiar.
The second time we stayed at a Studio at OKW, and I slept with the girls in one bed and my son slept with my mother in the other bed. Totally not something that would've worked at home, they would've been too excited to sleep in the "big guy bed", but after a day in the park, they immediately fell asleep in the big bed, no problem.
The last time we went, we stayed off site, and that time we had a suite that had a California King bed. Our girls slept inbetween my DH and myself. Again, not something that would've worked at home, but didn't have any problems with them getting to sleep and staying asleep.
I guess I should mention that my DH and I have no problem with our children sleeping with us!
If you don't want to go with 2 pack and plays I would use the air mattresses that the pp mentioned. It can be very tricky to set up bed rails on a pull out, and you may not want to have to mess with that when you're sleepy.