Most of the lines at WDW are what is called "Mainstream Lines" which means people with wheelchairs wait in the same line with everyone else. So, havinga wheelchair does not allow you to get ahead in line -basically what it gets you is a place to sit while you wait.
Here's a
link to the official Disney website page about mobility disabilities, which has info about Mainstream lines. If you scroll up a ways from where the page opens, you will find park rental info.
Rather than a wheelchair, you might want to consider an
ecv (electric
scooter). They are farily easy to drive and allow more independence (plus no one needs to push you). There are limited numbers of
ecvs available in the parks and they might be all rented when you get there -especially if you are arriving at the park later in the day.
The resorts do have a limited number of wheelchairs to loan out (they can't be reserved ahead of time). Some people have had good luck and other found them to not be in good condition or not be the size they needed.
Here's info abour outide rental places. If you only needing to rent for one day, you might be better off just renting at the parks, but for longer time periods, it's less expensive with one of these companies.
Care Medical:
http://www.caremedicalequipment.com/
Phone (407) 856-2273 Toll Free U.S and Canada (800) 741-2282
Walker Mobility:
1-888-726-6837
www.walkermobility.com
RANDY'S Mobility is in Kissimmee 407-892-4777
http://randysmobility.com/
Colonial Medical
http://www.colonialmed.com/about_cms.html
(800)747-0246
http://www.scootaround.com/ Not much feedback. Several people who reported they had no problems.
