I'm going to have to back up Bones Justice on "The Great Brain Robbery" of JLU being one of the best body switching episodes (for the actors not switching voices and for quotes like "That's not restful". I'd say why but I don't want to start another 3 or so page discussion on it)
I also give credit to Dragonball Z for using it (well Ginyu for using it to switch bodies with Goku and then a frog. Part of me also wants to count the Bulma filler switch episode but otherwise no) as an actual plot point instead of just as a one episode thing that otherwise had no impact on the continuity really. I think the only ones that did were more indirect. Teen Titans "Switched" actually did have Raven and Starfire's character grow as friends afterward, and Ben 10's "A Change Of Face" body switch allowed Gwen to get that magic book.
Man now I"m up to 7,000+ posts. Hard to believe it took me 8 something years to get that many. How long will it take me to get another thousand? Guess you're going to have to keep reading what I have to say to find out.... I hope you've been doing that anyway as I feed off the attention.