CSU definitely does not have the best girls in colorado... and it is a fact that a lot of students who attend CSU did not receive acceptance into CU. If you want to be close to mountains, I'd highly suggest Boulder.
Boulder has flat irons literally 5 minutes from where I live that I hike all the time, and Breck, Keystone, A-Basin, Loveland, Eldora are all less than an hour and 45 minutes away, on average, not no traffic or heavy snow...
Boulder is a chill place to live, everyone smokes weed and is really chill. Also, if you're into music, the fox theater located just across the street from campus has some of the best artists on the scene come through quite often.
for example, Sam Adams, Wiz Khalifa, Skrillex, Swollen Members, and J.Cole have all been here within the past 2 months.
Boulder is voted as one of the prettiest campuses in the nation, and I'd have to agree, its beautiful here. Now, it is true that a lot of California kids go here, but thats not to say you wont meet really chill and fun people, a majority of the people I hang out with are from California but they're from all different parts and you learn about some cool shit through them.
All bias aside, colorado in general is a great place to be, theres tons of colleges and universitys here, a lot of them actually located in a mountain environment so best of luck to you