Unfortunately, not all movies benefit from later retouches. Too many of them with added scenes end up adding something that ultimately detracts from the original film. The Star Wars movies certainly fit this bill. While some added shots of the space ships and scenery are appreciated, each movie adds something that bothers me (the most offensive being Luke's scream as he falls towards the camera after losing his hand in Cloud City).
That said, there are at least two (other than the Lord of the Rings) which make a significant improvement. The first is Star Trek II: The Wrath of Khan. While the added scenes lack the polish of a theatrical release, they finally explain why Scotty was so upset at the loss of the young crewman: the crewman was his nephew. The second is the Daredevil movie. While its theatrical version was not that good of a film, it turns out that it only needed a few small adjustments. The director's original version of the film captures much of the essence of the superhero while showing some of the sacrifices that Daredevil has to make. The changes for the theatrical release make the character more shallow, create a forced sex scene, and provide an anti-climactic final battle. I actually recommend that people watch the director's cut of the movie.
Many extended version, director's cuts, and unrated cuts aren't worth the film they are printed on. It's a only a small few that actually add anything to the experience. With the Lord of the Rings movies, once the extended version comes out, I don't go back to the original theatrical release.