It's good that you're learning how to be vague in Japanese too... :p

the first of your two Colorado sentences is better. 雪がたくさん降りますsounds more colloquial (to my nonnative ears...)--but the second is okay too.

You forgot the most important "want to do someone". :)

Oh, that's easy, I already know that.

あなたをしたいです。 :)

But this is better:

私をしてほしいです。 :P

もらいたい is the -tai form of the verb もらう、which means "to receive," so it means "want to receive" (the way 行きたい means "want to go" or 食べたい means "want to eat")

ほしい is an adjective, but there's a verb 欲する (and 欲しがる) that means "to desire, to covet, to want"

So with もらいたい、the baseline verb has to do with receiving, and you're saying that you want to receive X, Y, or Z, whereas with ほしい the baseline concept is desire and wanting, without necessarily wanting someone to *give* you the thing. So あの本が’もらいたいです。(I want to receive that book. I want to be given that book.) but あの本がほしいです。(I want that book.)

It would be pretty weird to say "XX ga moraitai" to someone--it would be directly angling to have them get you the thing. Saying "XX ga hoshii" would be kind of weird too, but you could say it in an informal situation among friends without them thinking that you meant that you'd like them to get it for you. Especially if you put "na" after it (あのCDがほしいなあ。。。) (Man, I'd really like that CD....)