My siblings favorites (in Boulder) are Southern Sun, Sanitas, and Boulder Beer. Celestial Seasonings has their tea factory outside Boulder, and the tour is great. In Fort Collins, New Belgium is a must see cause it's free samples! (It's closed Mondays). It's not far from Old Town, which is a great area to walk around, nice restaurants, etc. Skiing can be really expensive, but you might be able to get a gondola ticket or lift ticket that just lets you go up and down (and hang out at the dining on the slope). That's a fun way of getting a sense (and getting around the snow) for cheaper. Traffic can be really bad going up I-70, though, so a mountain trip is best done overnight, IMO. It's definitely worth doing, if you can. Look into Estes Park if you want to experience the mountains without the ski crowd. The YMCA there is great for activities (If you're looking to stay in the mountains on a budget that's a good option). The Stanley Hotel is fun to check out, too (it was the inspiration for the Shining)
There's lots of cheap Mexican and Tex-Mex food in CO. I'd check Yelp for those.