Here's some to try out:
In Estes Park:
http://www.cottageblissestes.com/index.html
http://www.mtnladyquilt.com/
Denver area:
http://www.threadbearquilts.com/ (Longmont)
http://www.greatamericanquilt.com/ (Denver)
http://www.fabricexpressions.com/ (Littleton/Denver)
http://www.harriethargrave.com/default.asp (Wheatridge/Denver)
http://www.emilyssewing.com/ (Lakewood/Denver)
Need any more suggestions? Along the "front range" of Denver and into Wyoming there are many very nice shops. You'll have a good time exploring, I'm sure!