Haven't lived in the other cities you have listed, but am considering move to Seattle, Portland, Nashville or ? lol so your post caught my eye. I live in Denver, with kids in your son's age range. Fantastic place with lots of options for variety in the various suburbs.
With the legalization, there are quite a few people moving into Colorado. Vacancies are hard to find, scams are on the rise, and rents are on the high side. Good news is employment is great, wages are above average, all major sports exist in the city, transit is user friendly and above average...you can definitely get around without owning a car and without being inconvenienced.
I moved here from AZ and summer desert heat, never having experienced winters, and Denver is situated in such a way along the mountains that it really doesn't suffer the way other areas do. It may snow for a few days, but all the while the sun is usually shining at some point and the snow is melting quickly. It doesn't stay on the ground for days/weeks like it can in other areas (of course, like Chicago, we've had our record-breaker winters that were uncommonly cold or had alot of snow, but for the most part, it snows for a day or two, then it's sunny and melts away....then it snows for a day or two lol and then it's sunny again); summers get hot so you can enjoy the lakes and outdoors and be reminded of the summer heat in Texas, but breaking up those two seasons are an awesome spring and beautiful fall.
There are wildlife reserves in the area, easy access to mountains, diverse community, decent night life for singles, crime isn't bad (not counting the high number of high-profile shootings Colorado has had), schools are decent and there are an equal number of oil/gas opportunities to green jobs, especially in local farm markets, farm-to-table movements, solar and wind production.
Hope this helps. Contrary to what people are hoping, Denver has not dissolved into a stupor, kids are not toking up on the corner and the cartels have not taken over
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