Hi Diane,
Thanks for visiting the Disney Parks Moms Panel with your question. A three-week visit to Walt Disney World sounds absolutely wonderful!
You are correct in that the second sleeping surface in both a deluxe studio and a one-bedroom villa at
Disney's Saratoga Springs Resort & Spa is a sleeper sofa. The difference is that in a studio, it is a double-size sleeper sofa, and in a one-bedroom it is a queen-size sleeper sofa.
My mother has visited Walt Disney World with us and stayed on the sleeper sofa in a one-bedroom villa at a Disney Vacation Club resort. She reported that the sleeper sofa was comfortable; however, you should know that she does not have health issues. She also said that since she had been running around with our daughter in the theme parks all day, she was exhausted at night and pretty much fell asleep right away and slept soundly through the night!
I hope that these thoughts are helpful for you, Diane. Have a wonderful time planning your vacation, and please do not hesitate to ask if you have any further questions.