I live in Longmont and we travel north just a bit to the Snowy Range in Wyoming. (Due west of Laramie approx 25 miles) Pretty much our regular spot anymore. 2hrs to unload and there is rentals (Yammy) up on the mountain.
it's a little bit of a drive, but grand lake and winter park have some of the best kept trails with great views. Power World in Granby rents sleds, both 600's and 800's.