Hi Sue, I have not tried Buena Vista Scooters, But I am sure they are great..
We have used
Scooter Rentals Orlando, Disney World ECV Electric Scooters at Scootarama.com 4 times & think their service & scooters are great too.
I think you would be smart to go ahead & get both parents scooters. Let me tell you your dad may think he can walk the parks but being on his feet for hours & hours will take it's toll. My Dad (84) thought he could walk, But soon realized how nice a scooter was. He had a wonderful time & felt great after a day of scootering.
Deb