And the two follow ups for The Empire Strikes Back and Return of the Jedi. Although most people consider Empire the superior of the original film trilogy when it comes to the radio dramas Star Wars is the best and the quality would go down quite a bit from there. Return in particular suffers from the fact that it was made at a *much* later date than the other two and has almost no members of the movie cast represented. In the first two Mark Hamill provided the voice for Luke Skywalker and Anthony Daniels the voice for C-3PO and for Empire Billy Dee Williams reprised his role as Lando Calrissian. By the time Return rolled around neither Hamill nor Williams agreed to be involved and both roles were recast... and it just wasn't quite the same.
As someone who really, truly loves the old radio shows, discovering this when the Star Wars edition was remastered, packaged and sold back in the 1990's was a Godsend. The story actually comes off very well even when you can't see the visuals and it expands upon the events in the movie. Some of the extra stuff is padding but others of it deepen motivations and characterizations. For example, we get a scene where the data tapes are delivered to Princess Leia and we get to actually meet Leia's father, Bail Organa (long before Jimmy Smits played him in the prequels). We also get several scenes with Luke and his friend Biggs which give greater weight to Bigg's death later on.
And here's an interesting trivia fact -- Biggs had a greater role in the movie version of Star Wars as well but all of his scenes hit the cutting room floor (only one was later restored for the "Special Edition" release) and if you listen to John Williams' soundtrack for the movie, the music builds to a crescendo culminating in Biggs' death -- which was supposed to be a dramatic moment as Luke's friend, and his last tie to Tatooine, died. Even though the character ended up mostly excised from the movie the crescendo stayed in the score.
At any rate, the trilogy is, on the whole, delightful to listen to. For years I've used them on long driving trips to entertain myself but it's also fun to listen to after dark. Turn off the lights, stretch out on the couch, and let your imagination paint the scenes.