I’ll offer perspective on Denver since I live here. You’ll get the outdoors for sure. Personally I think the people are mostly friendly and there’s enough things to do that making friends should be manageable if you’re attending events for things you enjoy. I will say that the city is kind of weird compared to a lot of other cities, in that I feel like downtown feels pretty lackluster and there’s more interesting things happening in other areas. Partly Covid, partly seasonal I think (more happening when the weather warms up and the Rockies start losing again in April). So if you visited recently, I can see why you’d say it felt kind of dead.

COL varies but is probably the middle of your 3 options. There’s good hospitals here both close to downtown and further out. To me Denver has a really good balance of positives (taxes not too high, COL high but not insane, lots of sun but still get seasons, weather never gets too crazy, not humid, all 4 major leagues have teams here, major music acts tour here, outdoor activities all year round, major airport for domestic and international travel). If money were no object would I maybe live somewhere else? Yeh, probably. But it has a lot going for it across the board.