I've lived in both locations and overall the cost of living is lower in Dallas than Denver, but the quality of schools and such are about equal between the two once you get outside of the "city and county proper" in both locations. The economy in North Texas has been stated to be more recession resistant than Denver, but I've never seen any report quantify it more than a list with Denver ranking lower than DFW. There's also more to do and places to go within a tank of gas in Dallas than Denver without talking about spending several hundred dollars at a Ski Area. If you like to Ski or Snowboard, there's plenty of affordable packages available to go up to Colorado from Dallas anyway.
The real question you need to answer is what climate you want to live in. This is the only major difference between Denver and Dallas. Do you want to live in a place with a winter that composes mostly of ice events on 3 or 4 days a year and cold the rest (usually in the 40s and 50s) and summers with a very humid heat, or do you want to live in a place that has thinner air, hot, dry summers, and plenty of snow and cold (0 degree lows are not uncommon) in the winters?
To be honest, I've worked the ramp in Denver and Dallas both in winter and summer. That's about the only difference I've found between the two. It's sticky heat in the summer and sticky cold in the winter in Dallas, and dry heat in the summer and very cold in the winter in Denver. It just depends on whether you'd rather sweat a lot in the summer in Dallas or freeze your butt off on the ramp during winter in Denver.
