I've shopped off & on at Neptune's since I took the CMC's mountaineering class in the mid-1980s. Always got good product and experienced good service. Living in southeast Denver and then Lakewood, getting up there required either a special trip or stopping on the way home from RMNP or nearby.
Couple people mentioned Galyan's. I remember it, while growing up in Indianapolis in the 1960s, as a little hole-in-the-wall hunting & fishing place out in a west side suburb. Was a real big deal, when I was in college, also in Indiana, when Galyan's opened a second shop near the state fair grounds on the east side of Indy. They obviously got bigger after I left town for Colorado.