The human-diaspora universe of Heinlein’s Time Enough for Love sounds like a lot of high-tech fun. And no matter what kind of human culture you’d like to live in, you can probably find a planet to your liking.
I’m torn three ways, between ST:TNG, 221B Baker Street and Middle-earth.
But if I’m in TNG, a proud citizen of the United Federation of Planets, I can fly around on starships to my heart’s content and still go to the Holodeck for Middle-earth and Holmesian adventures in perfect safety. Sounds like a plan to me. Sign me up!
Just make sure you don’t get the sentient version of Moriarty or your Holmesian adventure will take a decidedly technological turn that is not in keeping with the spirit of the books. 
Northern Exposure would be my first choice. I get Chris.
- Culture
- Known Space, just pre-Ringworld era.
- Foundation, just post-Mule era.
- B5, post-plague.
… but what’s all this I hear about Discworld being fictional?
Lots to choose from.
Pern
the Golden Age of Mysteries, British version (ie an estate, landed gentry, old money etc)
Georgette Heyer’s Regency England (but noone else’s-not a bodice ripper type of chick)
Hogwarts
Jane Austen’s world (Elizabeth Bennett’s)
Eragorn’s world
Subtle Knife’s world–His Dark Materials (especially the world where the creatures use those seed pods to move)–maybe just visit Pullman’s world; it’s a bit intense.
King Arthur’s world–without the plague and bad teeth…
House On the Strand world…very cool.
Star Trak, but only with Picard or the woman captain–I would smack Kirk right upside the head. Then again, I could kid with Spock. Hmmm…only visit here as well.
Hyperion verse POST novels. Teleport at will, sign me up.
Failing that, SG1 universe. Sure, Id likely be some menial earth person like I am now, but there is a CHANCE at ascension, and that is my kind of universe.
That, or like everybody has said, STTNG universe.
Would anyone like to live in a telepathic group-mind? E.g., The Mind of Spider Robinson’s Deathkiller series – which is a lot like the Borg Collective only, you know, nicer. And you don’t have to wear implants. Or the Starmind of the Stardancer series, which is similar, except you live in outer space with no spacesuit, just the symbiote, and you don’t have to worry about food or waste disposal – the symbiote takes care of all of that.
Another vote for Heinlein’s multiverse, especially a) The Luna of The Moon is a Harsh Mistress, and b) the later eras of Lazarus Long, such as Tertius. Though isn’t everything kind of interconnected?
I’ve never read any of the Culture novels; they look interesting.
I always liked the Humanx Commonwealth, as well. And Niven’s Known Space too, either the internationalised Golden Age before humanity meets the Kzinti, or after the Man-Kzin Wars.
Of course, there’s also the attraction of being a hobbit in the Shire…
The Star Trek world sounds like fun, especially because of the holodecks. But I suspect that the average citizen doesn’t have free access to them.
Ursula LeGuin’s The Dispossessed. I’d love to live in a functional anarchy.
On DS9, Quark’s bar has holodecks. He rents time to anyone who has the latinum.
I read that as The Pomoverse at first glance.
::visualizes a world populated exclusively by nonsubjects who are always already overdetermined by the discourse of pretentious polysyllables::
Discworld definitely gets my vote, too, but I’d make a quick stop by Neverwhere.
How about living on the good starship Serenity?
That’s my point. The Star Trek universe (and really any other) might be a lot of fun for the privileged, but not so much for the average person.
The Foundation (a la Asimov). Sometime after the fall of the Mule, or perhaps a liftetime before the Mule’s arrival.
But only if I can discount all the books from “Foundation’s Edge” on! 
Would being in a holodeck technically be considered existing in a fictional universe, in the Star Trek universe?
Anyway, I’d like to live in Bloom County. Just 'cuz…
The “Mirror, Mirror” Star Trek universe (with the piratical Terran Empire) might be really fun for the privileged! Provided you don’t get assassinated . . .
i would love to be the new muggle studies teacher at hogwarts
Might is the operative word—we see fairly little of civilian life in depth in the Trek shows. It’s like trying to evaluate American society based on what we see in WWII movies.