We rented a crib every time we went- I'd say about 4 times? We rented one from A Baby's Best Friend. We got the crib/mattress and bedding. They deliver it right to your room, and it's a full-sized folding crib with a flat sheet, blanket, bumpers- I think that was it.
We were EXTREMELY happy with our decision to rent from them.
With us as well, we wanted to guarantee a great sleep while at Disney, and that was for both us and our DD. She sleeps way better in a crib than a pack n play, and we are extremely happy with our decision.
We always rented a one-bedroom, so we moved a chair or whatever and would put the crib longways against the living room window, flush against the closed curtains, blocking out all the light. Then in the morning we'd just open the curtains to let light back in.
Again, very VERY happy with our decision, and with the company.
Good luck!