My knowledge of it is only secondhand.
It is (or was) back in the corner of tomorrow land between the exit for Buzz Lightyear and the Carousel of Progress.
I have never been a AAA member and not enjoyed the benefit of that particular lounge.
However our family was fortunate enough to enjoy the (now closed) lounge at Space Mountain that had a nice air conditioned seating area, free cold drinks and when you were done enjoying your respite, an escort to the front of the line for the ride. It was sponsored by the folks at Federal Express. In fact it was so long ago that it was pre fastpass days as they used the right side line to take us up for the ride with no wait. That and the AAA lounge were the only ones we "knew" about at Magic Kingdom.
Now EPCOT, that is a different story with several VIP lounges that have been and gone and some that are still there.