It's a no-brainer. Denver is the best city in America. I lived in Houston for 5 years, and Houston-to-Denver is a really favorable move.
PROS:
-Weather: always sunny, little humidity, great temps
-Parks/trails/exercise: I'm pretty sure Denver has the most parks and trails per capita in the nation; it is amazing how active people are here compared to TX
-Outdoors: In addition to the parks, there are so many opportunities around Denver and within 90 minutes for hiking/day trips/enjoying scenery and nature: Summit County, Golden, Evergreen, Colorado Springs, Estes Park
-Size of the city: Denver is just the right size. Denver proper is maybe 700k, while the metro area is a little over 2.5 million
-Downtown Denver is very alive and happening, especially compared to Downtown Houston. There are tons of great restaurants, bars, shops, and things to do. 16th Street pedestrian mall is great, with a free bus.
-Neighborhoods: There are several great neighborhoods within a 2-3 mile radius of downtown. Tall trees, historical buildings, and tons to do. Also, there are many great suburbs: Lone Tree (where I live), Highlands Ranch, Littleton, Denver Tech Center, Castle Rock, Parker, Golden, Centennial, Westminster, and a few more.
-Lack of crime: Denver feels essentially free of crime after moving from Houston. I work downtown, and I've never felt threatened.
-Golf is a huge upgrade over TX golf. Great courses, cheaper than Houston, and amazing views
-Beer: best beer state in the nation
-Pro sports: we have all of our stadiums in downtown or connected to it (football, baseball, basketball, hockey)
-Rocky Mountains: best skiing resorts in America within 1-4 hours
Hunting: if this is your thing, we have a much greater variety of animals here (elk, black bear, moose, mountain lions, and more)
-People: the people are laid back, want to have fun, friendly but not overly so like Texans are (which I like for the most part). It's more about what your hobbies are here vs how much money you have.
CONS:
-No Whataburger: I'm being serious.... this is really the only thing I can think of. Oh, I guess it is a little more expensive than TX. My property taxes are 1.5% less than Houston (right at .7% vs 2.2% in Houston). I got a steal on my house, and I doubt it would be cheaper in any Texas metro.... and it's in a "Best Places to Live" suburb. In general though, I would expect to spend about 30% more on a house. Renting is pretty cheap though.