I interviewed at the Children's Hospital in Denver a couple months ago. I had a fantastic time and the new facilities definitely make the ambiance / environment that much more impressive.
With respects to research opportunities, there are many. They are heavily recruiting more faculty to join their already strong clinical and research programs. The residency program is associated with Denver Health Medical Center (community health), the University of Colorado Hospital and National Jewish Medical and Research Center. Since the campus has the children's and adult hospitals next to each other, you are able to pursue inter-diciplinary research. My understanding from my interview is that while residency is busy, if you want to pursue research opportunities, that is available for you. If this is of interest to you, be sure to request an interviewer in your respective field of interest.
As for friendliness of staff, can you expand on this? Overall, I found staff in peds universally helpful. I didn't have any different vibe at Denver Children's.