Ignoring the Bronco stench, moving to Colorado has been the best life decision I've ever made. Our economy is (comparatively) thriving, our government is fairly moderate (albeit contentious as most governments are these days), our cities aren't excessively crowded, and I'd put the state in the top 5 in the country for outdoor activities. If you're a pot smoker, there's an obvious bonus there, but it's not a huge part of the culture either.
Drawbacks are mainly that everyone else is figuring this out too, so there are people everywhere. There are better states to live in if you don't like crowds.
As for Boulder specifically, it's a world of its own up there. It's gotta be one of the most liberal cities in the country, and it's also one of the more expensive cities to live in in Colorado as well. As a left-leaning centrist, it's a bit much for me even, but I know a lot of people who love it. Just be sure you know what you're getting yourself into.
