Hi Rosemary,
Thanks so much for visiting the Disney Parks Moms Panel with your question. I absolutely love
Disney's Old Key West Resort. I really like the laid-back, Florida Keys theme. It is truly a relaxing resort.
You are correct in that the resort is quite spread out, and that if you request a room it is not guaranteed. I have very often found that if you make a room request that is general, it is more likely to be granted rather than a specific room number request. This way, the cast member assigning your room will know why you wanted the room as opposed to just a specific number. Also, I have sometimes checked in and found that my room request is not currently available, but if I am willing to wait a couple of hours to check in, a room in the location that I want will become available. That said, buildings 11, 12, and 13 are closest to the restaurants and pool in the Hospitality House area, so these are probably the buildings that you should request. I suggest renting a car for your stay at Disney's Old Key West Resort. You are able to drive up to and park very close to all of the buildings with villas, as well as the Hospitality House area. This would minimize the distances that your mom had to walk within the resort.
I hope that these thoughts are helpful for you, Rosemary. Have a wonderful time planning your vacation, and please do not hesitate to ask if you have any further questions.