G. Garfield Crimmins’ Republic of Dreams.
Pros: It’s perpetually 1935. Tropical French colonial atmosphere. Sidewalk cafés. Passenger dirigible service. Half-naked women everywhere. Surrealism.
Cons: Everyone’s a surrealist. Everyone’s also French. I would be under some social pressure not to wear pants in public.
I’d like to live in the world of the X-men movies. Where there are millions of mutants with unique powers. I’d be one of them.
I’d also like to visit Asimov’s earth.
The Future History of Heinlein, not the Crazy Years (which we’re already working our way through), but the 4000+ AD Time Corps/Tertius period. Why? Because no matter what the pros and cons of the other fictional universes are, you can always go visit them for the pros, and get away if you have problems with the cons.
Was that cheating? I’m sorry! 
Otherwise, I think I’d like the Wormhole Nexus universe of the Bujold Vorkosigan series. Pros: advanced medical technology, interesting stuff everywhere, a wide variety of cultures to choose from. Cons: Cetaganda. Possibility of interstellar warfare.
I want to live on Tertius, in the Heinleinverse.
pros
fabulous medical center
hot ambinguously sexual women
hang out with Lazarus Long
join the Circle and go dimension hopping
cons
dimension hopping = crazy dangerous
… uh…
I don’t look good naked?
Dang, I can’t think of many cons.
Ok, that may be the funnies Simulpost I’ve had ever.
Hehehe…
“Gay Deceiver… DOPE!”
EXECUTE!
ROFL!!!
(About that orange cat hanging out in your front yard, Tristan… ;))
I wouldn’t mind Tertius at all.
I also wouldn’t mind being a Dorsai, or a scholar on the Final Encyclopedia. Actually any of the Splinter Cultures except the Friendly worlds would be pretty cool. Just don’t put me on Coby!
Either the world of Doctor Who, or The world of Beetlejuice. Both are just like real life, but in the “Whoniverse”, the conspiracy theory are real, and if somehorrible tragidy happens to me, 5hier is a 33% chance I might not also get killed, but instead end up traveling with the Doctor, while the real world, ( not the underworld) of Beetlejuice is continually in the 1980s, and contains spell books which have simple rhyming incantations that really work.
At second thought, I would rather live in the Lum’s world, a.k.a. Urusei Yatsura’s Lum. Sure, horrible and bizzare things might happen, but for the most part they can be blamed on that no good slaker Ataru! Get back here, you lazy bum! I’ll get you for ruining my food stand with that** damned** alien juggernaut!
Xanth. For all that it’s poorly written, it’d be a great place to live. Pies grow on trees, everybody (even the common schmoes) has at least some degree of magical ability, naked and willing nymphs are all over the place, adventure around every corner, and if you manage to become a Major Character (for which the only requirement seems to be desiring said condition, regardless of whether there’s actually anything interesting about you), you get an impenetrable character shield.
Narnia would also be good, particularly during the Reign of the Four, when the biggest problem seems to be some minor sabre-rattling on the part of Kesh.
Ernest Callenbach’s Ecotopia:
Pros:
free love w/o STDs
clean air, clean water, clean living
unrestrained, let-it-all-hang-out self-expression is normal, even in public
for some reason the above rarely leads to fistfights
peaceful foreign policy
exciting internal mock-wars with spears; kills rare, injuries treatable, and you don’t have to be a professional athlete to join in the fun
materially sustainable society in the long-term (in the author’s vision, anyway)
free love w/o STDs
Cons:
what, no NASCAR?
I need a license to own plastic?
limited creature comforts
everything’s too labor-intensive
after two weeks on home-grown organic food you know you’re gonna be craving Taco Bell
maybe the author’s assumptions about sustainability are wrong
Neal Stephenson’s The Diamond Age:
Pros:
nanotechnology can provide for everybody’s basic needs cheaply
technological marvels we can barely dream of
skyscrapers made of solid diamond
interactive books can help every child realize full intellectual potential and make it fun
technology-assisted justice system it’s very, very hard for lawbreakers to beat
Cons:
Didn’t we used to have something called “society”? What’s with all these “tribes”?
unprecedented abundance of material wealth still seems, somehow, to have left a lot of people in the shit
and why is there this horrible war in China?
you’re sure the “grey goo” thing is impossible?
technology-assisted justice system it’s very, very hard for lawbreakers to beat
Myst Worlds.
Pros–
Beautiful, quiet, diverse and apparently customizable and rebuildable. Also, most worlds seem deserted so I could have the world all to myself.
Cons–
That seems a little lonely.
Rick Cook’s Wizard’s Bane universe
Pro’s
Magic Works
Software Programmers can do magic
Beutiful Red-headed witches
Con’s
All kinds of nasty monsters
No hot water or indoor plumbing.
Fu… I mean damn! I forgot about Discworld. I’d like to live in Ankh Morpork for a bit.
The fictional Okeefenokee Swamp, from Walt Kelly’s Pogo comic strip.
Plent o lunch, fishin, lazing in boats, good company, & Albert Alligator & Howland Owl to stir up something interesting every now & then.
The Cthulhu Mythos Universe
Pros:
if you look hard enough, you can find a copy of the real Necronomicon
magic that really works
ultracool stuff: fascinating mythology, non-Euclidean geometry, dark poetic visions, buried/sunken cities, prehistoric sentient races
if you’re the right kind of person, you can adventure in “Dreamland” without chemical assistance
no need to fret over conspiracy theories – if you’re in-the-know, you know it’s really like that, only worse
we can really know for sure what humanity’s place in the universe is: termites, infesting the Old Ones’ house
if you know too much, you can always fall back on your last (in some cases, first) line of defense: going insane
Cons:
you can only use the magic to summon the Old Ones or banish them
everybody who matters is a neurotic, scholarly, upper-crust New England WASP
every non-Anglo-Saxon is probably a product of cross-species interbreeding
nobody ever seems to get laid
everything is scary if you look closely enough
practically anything connected with the Old Ones smells even worse than it looks
in the end, we’re all lunch, if we’re lucky
I would like to live in the fictional universe inside George W Bush’s mind:
[ul]
[li]Infinite amounts of money can be spent regardless of how much you have or can be expected to bring in[/li][li]All the nations of the world are keenly interested in doing what you want them to do rather than what’s in their interest[/li][li]You have the power of Gideon to conquer anyone anywhere with an undermanned force[/li][li]God is on your side[/li][li]The past doesn’t matter[/li][li]Mistakes are never made[/li][/ul]
But failing that, count me in for The Hundred Acre Wood any day! 
DCU - Where I’d be nearly guaranteed to have a radiation accident that’d activate my metagene.
Dragonball Z Universe - Where, with mild weekly exercise, I can build up to weightlifting in one-hundred times gravity and firing energy blasts.
Mild and weekly aren’t adjectives I would use to describe their regimens, else Chi Chi and Mr. Satan would be flying.
I think I’d like to live in the Bazaar on Deva from Robert Asprin’s Myth world. Anything you want in the universe, if it can be found, can be found there. Con is that whenever dealing with a Deveel, if you think you got a good deal, first check your change, then check your fingers.