From 1977 to 2003, Pentax's USA headquarters was in Inverness Park in Englewood, Colorado, south of Denver. They had about 150 people in their two-story office with attached national distribution center/warehouse and in-house customer service center*:
35 Inverness Drive East, Englewood, Colorado - Google Maps
From 2003 until October 1, 2011, their USA headquarters is in the Clear Creek Square building in Golden, Colorado, west of Denver. They only occupy the third floor, and had perhaps 60-70 people there in 2003:
Pentax Golden Co - Google Maps
Pentax USA HQ - Golden, CO | Flickr - Photo Sharing!
Per the recent news articles, they're moving by October 1, 2011 to a smaller office (about 40 people) on the 26th floor of Colorado Plaza Towers at:
633 17th Street - Wikipedia, the free encyclopedia
633 17th Street, Denver - SkyscraperPage.com
I don't think they will have a walk-in service center there. More information about their post-move facilities and operations is posted at:
PENTAX DSLRs: Pentax moves to Downtown Denver, Colorado. Everything is looking good.
*Pentax's total USA sales (mostly film cameras, but also including sport optics, surveying, etc.) peaked in the late, pre-digital-camera 1990's at nearly $200 million. Considering that Pentax's
worldwide camera business has now been sold to Ricoh for about $120 million, we have some idea of how competitive the digital camera market has become.