fort collins sucks and it would probably be farther to denver than any of you would like. it's about an hour drive to get to the edge of denver from there.
greeley sucks even more... the constant smell of cowsh!t
of the places you named i've lived in pueblo, colorado springs, denver and boulder.
boulder is by far the coolest place to be... unless you like big cities and traffic because denver has that.
pueblo is only there because of the steel mill and it is really dusty and windy there and not very fun as a general rule... and its farther from denver than fort collins.
colorado springs is my least favorite of all of them... if you like getting told what to do by holy rollers then move there. it is a bigger city though and has quite a bit to do.
i love boulder although i just moved to lafayette which is 12 miles east. boulder is pretty pricey to live in and rightfully so. it is the closest to the mountains you can get without being in them. very beautiful city, not too big, lots of hot girls on campus, a 30 minute ride to denver and the best of all... its known for its "boulder blue sky" where sunny days average 300+ per year.
golden also seems like a nice place... i mean, if you like coors... you'd be set
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anyway, once you narrow it down to a city... i can help with neighborhoods too as i'm pretty familiar with many areas around here.
good luck and hope to see you here soon!