YAY FOR ESTES PARK!!!!!!!!!!!!!!!!!!! I'm a little biased on that, my dad grew up there, my grandfather still lives in the same house and my aunts live in Longmont and Dever. So basically for 20 some odd years all "vacations" were spent in cabins in Estes Park!! It's amazing! I can honestly say I've only been there twice during the winter months (and one of them was for my grandmothers funeral so needless to say, there was no "sightseeing" stuff).
One of my favorites is Horseback riding. There is one just outside of the entrance to Rocky Mountain National Park, and you ride into the park.
Trail Ridge Road - highest continuous highway in the US will be closed. This is located in Rocky Mountain National Park. You can still drive into the park, but will NOT be able to get to Alpine Visitors Center at the highest point.
A great thing about Estes Park is the wildlife that just roams around the town. Litterally the Elk will bed down in the middle of Main Street, and you just move around them.
Estes is located about an hour and a half north of Denver, and there are a ton of things to do in Denver like the Aquarium and the zoo.
Sorry if I totally bombarded you with too much information. I just get so excited talking about CO!! Please let me know if you have any quesitons...if I don't have the answer, I know people who do!!