Only Star Wars books ive read are the "X-wing series" which looking back where kind of crappy, and Shadows of the Empire, which was ok (I personally thought the soundtrack was the coolest part to come out of that whole thing). I hear Heir to the Empire is a good series but I'm a little hesitant because I really don't want to get caught reading a starwars novel by someone I might know.
The Thrawn Trilogy (Heir to the Empire / Dark Force Rising / The Last Command) is THE best Star Wars story since The Empire Strikes Back. Timothy Zahn absolutely NAILED it. Hell, his hints about the Clone Wars were FAR and away better than what Lucas came up with. He even got to name the Republic/Imperial capital (the very first MENTION of Coruscant was in Heir to the Empire).
The X-Wing series was actually very well-done, with lots of fun Easter Eggs (@#$%ing Redemption Mission...) and did a wonderful job fleshing out secondary film characters like Wedge, Tycho, Hobbie and Jansen. There was a heightened sense of danger because you weren't dealing with any major characters so you there was a genuine possibility of characters dying (but without overdoing it, unlike SOME writers *cough*Martin*cough*), and Stackpole (who's an easy #2 on the list of best Star Wars writers) worked very closely with Zahn, which is why their respective books mesh together so well, and actually FEEL like they're part of one universe, while most of the rest of the EU authors just did whatever the hell they wanted, which helped greatly contribute to the very disjointed feel of the EU. (Stackpole's I, Jedi and Zahn's Hand of Thrawn Duology even work together as a pseudo-trilogy).
And Allston's books in the series were HILARIOUS. The Ewok Pilot running gag especially had me in stitches, but it was also the Wraiths' general insanity. Also, Jansen, full stop.