Don't be too worried about there being a lot of walking involved at the Mayo complex. There are always volunteers and employees ready to help with directions. There are also plenty of chairs and benches for those who want a break from walking. If you decide you need a wheelchair, they are scattered all over the place free for anyone to use.
The buildings are connected by an underground hallway "subway" and by a second floor "skyway" system. Some restaurants, hotels, and even a shopping center are accessible by it, too.
Everyone there is happy to help people any way they can. They understand there is a lot of stress involved for patients and their families.
Good luck with your visit! You are in good hands!