We went to Disney last year when DS was just shy of 3. He loved his crib so he stayed in it until just after 3 when he move to a twin with bed rails. I wasn't about to give up the crib before 3 if we didn't have to! At Disney we just got a pack n play and brought our own sheets/blanket. He loved it and slept fine (and it was free). Now when we travel we use this and love it:
https://www.walmart.com/ip/Intex-Toddler-Airbed-Tan/22899906
He couldn't have shared a bed (with ANYONE) at that age and probably still couldn't. If he fell out of a bed he'd lose his mind and wake us all up which is why I love the toddler air mattress. He's fallen out of bed 3 times even with rails up in his twin, that's how much of a crazy sleeper he is. And two out of 3 times that has resulted in a massive nose bleed that takes two people to deal with.
However, I have many friends who's kids share beds with no problem, or use an air mattress (or regular mattress) on the floor and if they roll out they just get back in. It's definitely kid dependent. I wouldn't be trying the sharing a bed for the first time at Disney. If you've done it before and it's worked out then I'd do it in a heartbeat.