Actually it worked pretty well for us, because...well, Disney.
We also signed up for the buses, it was easy-peasy in to Epcot (they even played America's Funniest Videos to entertain us--although I tend to find it more cringe-worthy than funny), then we did Epcot. A friend from Florida even met us there and stayed all day with us.
DO NOT MISS LA CAVA DEL TEQUILA.
After Epcot, wheelchair notwithstanding, Mom-in-law had enough and took an early bus back. Disney took care of her (wheelchair and all) and all we had to do was hand her off. Then we went to Magic Kingdom via the monorail--again, easy-peasy.
We knew we didn't have much time since it was so late, so I popped into Guest Services (two reasons--one, for a deck of cards for the game you play in the park, and two, to get some recommendations). I explained that we were in from the cruise, we had about an hour and 15 minutes before we had to be back on the bus, and
Disneyland is our home park. I asked which rides were the "can't miss" rides so we wouldn't waste time. We were thinking of Pirates, and the cast member at Guest Services told us to go because it was different from California. We did three rides--Pirates, Haunted Mansion, and something else (I forget what), a bit of shopping, the game, and then that was it for the Magic Kingdom. We took the bus back to the cruise and off we went!
I remember our cruise card was our pass to the parks, and I think it may have even been our photo pass as well. I bought a photo of all of us in front of the castle, and used the photo mat signed by all the characters onboard as part of the frame. Such fun!
I just remember being nervous about it, but it ended up being very simple. They know how to do this--they've done it before and I'd be surprised if it weren't well-organized.
Have fun! We're envious--wish we could do NYC again, but we teach...so we're out. Our principals would never let us go!
--Karina