But... My wife made me a slutty female avatar in SR3 :-/

Yeah, it turned out she wanted to be the only one with a slutty female avatar - but I still think its good advice in general ha ha ;)

Scribblenauts Unlimited (The ability to create any new character from complete scratch and give them traits and a personality)

Towns (Manage a growing community, not a lot of interaction between characters but a great godcomplex game)

Spore is a good suggestion aswell, though there isn't a lot of interaction between characters in your own tribe.

General character creation games that are worth checking out would be Vampire the Masquerade Bloodlines and Skyrim (with mods you can't really beat this one)

This doesn't fully fit your criteria, but I know more than a few people who spend HOURS setting up their oblivion characters.

A quick google image search shows quite a few options:

[url=https://www.google.com/search?q=oblivion+character+creation+face&client=firefox-a&hs=dAS&sa=X&rls=org.mozilla:en-US:official&tbm=isch&tbo=u&source=univ&ei=5A62UbXIFuaV0QGtvoCQAQ&ved=0CC8QsAQ&biw=1920&bih=835]https://www.google.com/search?q=oblivion+character+creation+face&client=firefox-a&hs=dAS&sa=X&rls=org.mozilla:en-US:official&tbm=isch&tbo=u&source=univ&ei=5A62UbXIFuaV0QGtvoCQAQ&ved=0CC8QsAQ&biw=1920&bih=835[/url]

Some youtube examples: (not the best, but check out the side links on topic as well)

http://www.youtube.com/watch?v=kK4ZP-wdk5E

I stopped playing SR3 for awhile now in order to play (and finish) SR2 first... but now I am a bit perplexed why the game keeps telling me so much about where I can buy new outfits, what my wardrobe is like etc.

Do those different clothes really matter for the gameplay (e.g. different missions require different clothes), or are they just some useless gimmick? What is this, "Queer Eye For The Straight Guy - The Game"???

I recall in GTA Vice City you sometimes needed to go change your clothes before going for a mission, but I didn't really get the point there either. And I think it was only certain missions anyway.

is fun but has no character creation you play with the characters provided and evolve them.
The Movies has a feature where you can create characters and use them in game where you also if you want can control what they wear and how and who the they interact.

Thank you all VERY much for y'all's suggestions! I'll comb through them and see if she's interested in any :)

Right now though, she's been watching TobyGames' Minecraft videos, and she really wants to try that lol! I'm planning on getting it for her when I get payed next week, but if anyone has a key for it, I'm not beneath accepting charity ;)

I didn´t know TinyE was one of the developers of Legend of Grimrock...
;)

Perhaps one of the older Sim City games (only 2K here, but steam has the rest of them). No character generation, but at least you can play God and destroy the town. It just takes a while before it is satisfying to destroy the town.

Maybe "The Movies", you can choose costumes, actors, film plan and directing own movies.

How about the good oldie MadTV? Then she will learn how hard it is for a man to please the girl of his dreams!

My girlfriend liked to play: World of Warcraft, FarCry, Crysis 1, Crysis Warhead, Plants vs Zombies.
One of these could be a good choice.

As much as I love the Creatures games from what you're writing it isn't what you or your girlfriend are looking for.

How about Morrowind?
She can create a character and even after that there are a lot of different items to choose from in-game to customise that character apart from skills (jewellery, clothes, weapons..), and she can have her own dwelling (and even partly furnish it) later in the game.