Mushroom Kingdom - spanking some Princess asses. Mario obviously doesn't have the balls to do so.
Hyrule - the same as above and Triforce, nuff said.
Kotor 1 - becoming a Jedi.

Pokemon is the only answer to this question. If you say anything else, you are only hurting yourself.

The Last of Us, Resistance, TES/Tamriel.

tetris
pong
puzzle bubble

Pokémon World, it would be so fucking awesome! AND I would never get old!

Pokemon. Ridiculous levels of friendliness eveywhere and no big dangers.

Monster Hunter would also be pretty cool, you get to kill giant monsters AND you are immortal, because little cats always save you.

Hyrule,
Mushroom Kingdom,
Dragon Ball Z (who hasn't dreamed of becoming a super saiyan)

1.) Well, Pokemon is the obvious choice. A big world to explore, you have not to work. There are no dangers for you, you always send the Pokemon to battle for you. Also this let you win enough money. Your parents have no problem with you traveling into other cities on your own. And everyone you meet is giving you presents. What can go wrong with that? It's in no way dangerous, but on the other hand you get enough fun so it is not boring either.

2.) I have to agree with Snyps about DOA Volleyball.

3.) Well, the world of Xenoblade Chronicles is dangerous. But it is too awesome to miss out on it.

Mass effect- ok this is not a world it's fictional universe based on our own but I'd like to live in this universe.

Eorzea- stunning landscapes, different races and deep cultures, chocobos, fantasy and magicspells -Awesomeness

Fallout 3- simply just to see if I could survive in a post apocalyptic world. And it's the only one I could think of that's different to the two I just picked!