Might be chilly, but there are great places to warm up on Pearl Street.
Visit the famous flatirons. Don't die soloing.
The Boulder Dushanbe Teahouse was created as a gift to the city of Boulder, Colorado, from its sister city Dushanbe, the capital of the Tajik Soviet Socialist Republic, then part of the Soviet Union and now Tajikistan. The interior is beautiful.
Greg and Ruby's Favorite bar in Nederland. We recommend you visit Nederland anyway just to say you've been!