My favorites are Kashyyyk, Manaan and Unknown World (in that order).
I love the nature in those worlds, especially Kashyyyk (oooh, treeees), but, like so many here, found the Selkath rather annoying because of their attitude (went to prison twice, got executed once) and their camera-off message.
Off topic: Serpentine, you wondered how they got the sound... well, I think I've got it, just need to check it, so next time I visit Manaan and it turns out to be okay, I'll upload it.
[EDIT] I've got it! They made that selkath sound just by speaking this weird speach into the microphone (often accompanied with some saliva, you know) and then they'd pitch shift it down and put some reverb on it, perhaps even a little flanger, at least that's what I did [/EDIT]
Last edited by MrMarius; 03-19-2008 at 08:26 PM.