The disABILITIES FAQs thread has a list of attractions with Mainstream Access in post 11.
This is a link to that thread:
http://www.disboards.com/showthread.php?t=595713
You can also follow the link in my signature or find the thread near the top of this board.
Animal Kingdom and the Studio were actually built with all Mainstream lines (although a couple, like Dinosaur, Kali River Rapids, the Safari and Toy Story Mania have different accessible
loading areas, they still are Mainstream lines to that point.
Most lines at Epcot and MK are also Mainstream and have been for a long time. The few in any of the parks that are not Mainstream had something that made them inaccessible.
Some, like Haunted Mansion, were able to be changed to be made Mainstream.
Some, like Small World and Spaceship Earth, could not be and do have an alternate accessible entrance.
Some, like Buzz Lightyear and Splash Mountain have a different accessible loading area, but are accessible to that point.
Guests do not need
DAS (Disability Access Service) to use a wheelchair in lines (guests did not need the now discontinued GAC - Guest Assistance Card - to use a wheelchair in lines either).
If it is busy, guests may be given a wheelchair return time, roughly equal to the Standby wait time, for these attractions which do not have Mainstream wheelchair access:
At MK
Jungle Cruise
Big Thunder Mountain RailroaPeter Pan's Flight
Small World
Space Mountain
At Epcot
Spaceship Earth
Guests who have a Fastpass for those attractions will be given a wheelchair return time with the present time when they present their Fastpass/ Magicband with Fastpass. They can go directly to the accessible entrance or the return time has a 1 hour window to ride.