I live in the Denver area and my favorite shop is
Holly's Quilt Cabin
http://www.quiltattic.com/ (don't know why their website is named the way it is). They have a nice selection of fabrics and the staff is wonderful. Also, try
Great American Quilt Factory http://www.greatamericanquilt.com/ The ladies there have written quite a few quilt books, it's another fairly large quilt shop. The good thing, if you're going between Denver and the Springs, is that both of these are not too far away from I-25, so they're both easy to get to for someone who doesn't really know their way around the area. Can't help you in the Springs, but maybe there's someone else on here who can. Hope that helps! :-)