OK, way later than I promised but here's a quick summary of music stores in Denver/Boulder, Colorado Springs, and Fort Collins. Keep in mind that these are my observations and your mileage may vary.
There's no really great bass shop in the area. If you want Fender, go to Guitar Center or Robb's Music in Boulder. If you want MusicMan, it's Guitar Center. If you're looking for something unique, there's honestly not much.
Denver / Boulder Area
Drum City – Guitar Land in Wheat Ridge has a very unusual storefront, more like a warehouse with way too much on display (stacked drums, crammed guitars). They do carry a fair number of higher end basses on their website – MusicMan, Fender Custom Shop, Modulus, and more. In the store the only upscale bass on display was a Modulus, and there were only a few other basses on display. Not really shopping friendly.
Guitar Center Arvada is a small sized Guitar Center. On the showroom floor they had a dozen MusicMan basses, and a couple dozen Fender products (Squier, Made in Mexico, USA). Only a small number of amplifiers were on display from Ampeg, Gallien Kruger, and Markbass.
Guitar Center Denver is the largest and most well-stocked Guitar Center of the five stores located in Denver, Colorado Springs, and Fort Collins. They had about a dozen MusicMan, and a dozen Squier basses, a dozen Fender Made in Mexico, and a dozen Fender USA basses on display. They also had a decent selection of amplifiers from Ampeg, Acoustic, and Markbass, plus one high end Mesa amplifier. There were no used or vintage basses on display.
Guitar Center Englewood is a small sized Guitar Center, very similar to Guitar Center Arvada. On the floor they had a 6 MusicMan basses and a couple dozen Fender products (Squier, Made in Mexico, USA). Only a small number of amplifiers were on display from Ampeg, Gallien Kruger, Markbass.
Musician’s Super Store in Westminster is “Guitar Center lite” (as someone else pointed out), all the way down to the central checkout and turnstile entry/exit and backpack check in at the register. The bass department had all low end mass market basses and amps. Lots of “selling” from the sales staff showing discount from list price that no one sells for (and most customers know this).
Music Go Round in Littleton is a typical cookie cutter franchise setup. Lots of low end gear, a few nicer pieces (e.g. an Ibanez Prestige for $1,000 and a Warwick Corvette for $850). The only item greater than $1,000 in this store was a Warwick FNA Jazzman, priced at $2,000.
National Speaker and Sound in Denver is primarily focused on the professional audio and sound system market, but happens to carry some bass gear. They had 6 basses in stock (1 Yamaha, 1 Nash, 1 G&L and a few low end products). 2 bass amps were in stock – a Hartke combo amp and a custom Mesa amp and cabinet covered in red “alligator” leather (about $4,000).
Rockley Music in Lakewood had only eight beginner basses in stock from Peavey and ESP, plus a few small practice amps. They claim on their website to carry a few high end bass lines (like Rickenbacker), but never seem to have any in stock over the last 12 years I’ve stopped in and didn’t have any at this visit.
Guitars Etc in Longmont is a nice store with friendly employees. They had a total of ten basses in stock: 1 Fender USA, 1 Modulus “Flea” signature bass, and the rest low end models. They only had a few practice amps in stock. Don’t bother with Miller’s Music next door.
Robb’s Music in Boulder is a nice store with friendly staff. They carry a lot of Fender product (Squier, Made in Mexico, USA), plus six import Spector basses (<$700). For amplifiers, they carry Eden, SWR, and a few small practice amps.
Wildwood Guitars in Lousiville really caters to guitar plays. Only three bass guitars were on display – two used Fenders and one Rickenbacker 4004Cii which was originally transparent blue, but has faded to purple by being displayed in the window. The website shows 3 Rickenbacker 4003 models in stock, but they were not on display. Storefront was a bit of a letdown.
Fort Collins Area
Guitar Center Fort Collins is one of the most generic Guitar Centers I’ve ever seen. Bass products include Squier, Fender Made in Mexico, a few Fender USA, and a few MusicMan. They had 6 small Ampeg combo amps, and a few low end Acoustic amps.
Spotlight Music in Fort Collins is a nice store, locally owned, with friendly employees. They had about eight low-end basses in stock (Fender, Ibanez, and ESP). The nicest bass was a Fender Steve Harris signature bass ($1,300). They had one used Fodera Victor Wooten “Ying Yang” model bass on consignment for $6,000 (it belongs to an employee). For amplifiers they had one Mesa with a 2x10 Mesa cabinet, a Mesa Walkabout Scout 15, and a Fender Bassman 300 tube amp with a 4x10 cabinet.
Colorado Springs
Colorado Guitar Emporium is a small locally owned store that carries a few low basses and is also a G&L dealer. There is not much inventory in stock. They seem more focused on lessons and service than sales.
Guitar Center Colorado Springs is a medium sized store, with a decent selection of low priced basses, most $600 and under. They did have 8 MusicMan basses on display. Amplification on display included 1 Ampeg SVT with a 6x10 cabinet, plus a few smaller amplifiers from Ampeq and Acoustic.
Music Central is small storefront in the same shopping center as Prosound Music Center. The store is overstocked and messy, with very little good merchandise.
Music Exchange has a great downtown location but very little inventory in stock, and what they had was all budget items that compete directly with Guitar Center. Their website makes it seem like they specialize in vintage and unique gear, but the inventory on hand says otherwise.
Prosound Music Center had about a dozen basses in stock, most less than $500 and all less than $1000. Nothing interesting to me.