Like I said...people ask me for my opinion. And I give it here instead of in email because now the rest of the world gets to enjoy the glory of my opinions:
Your website says you have an opinion on everything...I need an opinion
on cell phone service providers in Denver....
We use Cingular and are pretty happy with them. The coverage is solid around Colorado, though Sprint is putting out ads saying "best coverage in Denver". I'm not sure who is best around Golden specifically, but vaguely remember both sprint and cingular working fine up there. I just got a new sim card that will work in more international places - but I haven't tried that.
Verizon is also known to be pretty good. With Verizon you may have better international roaming options since they are part owned by Vodafone (largest international carrier).
T-Mobile is CHEAP, but the coverage is worth what you pay (i.e. the coverage is not good). If you don't care about getting consistent service and just want a lot of minutes for not much money, t-mobile is good. They also have cheap options for data coverage (e.g. to use with a blackberry) if you like that kind of thing.
Cricket is cheap considering the unlimited minutes and the coverage on the front range is decent. However, roaming is not free nor do they cover a very large part of Colorado and if you care about having any features (voicemail, call waiting) Cricket quickly becomes just as expensive as a moderate amount of usage from another provider.