Loading and unloading a scooter in a rental car looks easy when you look at a
youtube video. It's probably easy if you're traveling with young adults. Otherwise it can be a challenge.
I'm going to skip ADA rules in this post. I don’t know enough. Some posters, not in this thread, think they know more then they do.
Resort selection makes a huge difference. Guests at POP can ride the skyliner to 2 parks. One bus stop means you know how many scooters are ahead of you.
POFQ doesn't frequently share buses. You know how many are ahead of you. You can boat to DS.
The EPCOT resorts let you scooter or take the boat to 2 parks. Swan. Dolphin and Reserve will frequently offer AP rates and senior rates close to moderate rates.
Monorail resorts offer monorail access to 2 parks. Might even be able to scooter to MK.
Mears accessible taxi vans are reasonable.
Resorts with multiple stops or resorts which share buses can be a challenge. Early bus stops may find scooter spots taken by returning guests. Guests at the later stops may find the scooter spots taken by guests who boarded earlier.