Denver is a great central location with a lot going on down town. Colorado Springs has more sight seeing but is an odd odd place and not a lot of night action (unless you’re into sketchy)
Literally thousands of trails out here to hike/ride/run/etc but keep in mind most people can’t handle much of it. They just changed hanging lake trail from first come first serve to $12 tickets you have to get in advance. It’s an incredibly steep hike but well worth the effort for the views and now you can actually park and do it where as before it was near impossible.
Mt Evans is a great drive with great views especially if you take the back roads to get there vs i70.
Pikes peak is also a great drive with great views and you can couple it with garden of the gods and/or st Mary’s falls or seven bridges trails in Cheyenne mountain.
Honestly, Rocky Mountain national park isn’t the greatest. Always packed, people are inconsiderate dicks with litter and whatnot and you can see better views elsewhere. It’s the better part of an entire day too because it’s a fuck ton of driving.
The museums and zoo in Denver are top notch. You can donate and go to the animal sanctuary out east which is full of rescued big cats, bears, etc (and they need money for their move way down south).
You could also head to Moab if you wanted as it’s a 6 hour drive from Denver though middle of summer will be a scorcher. The national parks out there are amazing too.
Every mountain town from vail to estes park are all similar. Bunch of small shops selling over priced tourist stuff. Summer doesn’t offer a heck of a lot to do but there are zip line tours and gondola rides at most ski places like breck, vail, copper, granby.
Any more outdoor activity questions just ask. I don’t do the bar/party/night life thing so can’t help there.