Tattooine is right up with there with Courscant, IMO. Dagobah can go suck a Sith. You seen one swamp, you've seen 'em all.
In some of the comments people left, one or two jogged my memory - yes, how can they leave off the planet Vulcan? Or Geidi Prime from Dune? Or Krypton?
Heck, there are even planets no one has seen, but almost everyone has heard of in the Star Wars universe - Corellia (Han Solo was Corellian, remember?) and - well up until Ep III - Alderaan.
They guy who yelled "Barsoom" in the comments made me laugh. Yes, I remember that place!