Hi Tracy,
Yes, you can ride a boat from
Disney's Old Key West Resort to Downtown Disney, just as you did from Disney's Port Orleans Resort Riverside. The deluxe studios at this resort are beautifully appointed but you would be better off to reserve a one-bedroom villa at this resort if your daughters wish to each have her own bed. As I understand it, roll away beds are not available for the deluxe studios at Disney's Old Key West Resort. The one-bedroom villas, by contrast, have a queen size bed, a pull-out couch and a pull-out chair. Disney's Old Key West Resort is a charming resort with a subtle tropical theme and a fun pool. I think your daughters would enjoy this relaxing resort.
A more affordable option, though, would be to book a room in the Alligator Bayou section of Disney's Port Orleans Resort Riverside. Some of these rooms have a trundle bed that would give your daughters the opportunity to each have her own bed. Be sure to ask for one of these rooms if you choose to stay again at Disney's Port Orleans Resort Riverside.
Good luck as you make your decision as to where to stay during your next Disney adventure. If you need any additional information, don't hesitate to ask!
Best wishes,
Jill