Denver is awesome. Lived in C Springs for 3 years and we went there quite often. But the online/paper cost of living adjustment doesn't tell the whole story.
Everything is more expensive there. EVERYTHING. We moved from Norman OK to C Springs. Fortunetely I have a career that made affording the move easier (goverment adjusted housing allowance for high cost of living) but it still stung a good bit. They are a bit tax happy in Colorado compared to OK as well, so its a slight increase across the board and you don't realize how much until you settle in.
The general rule in C Springs as well as Denver is the closer you are to the front range, the more it will cost you. So Golden is really pricey, Lakewood and then Aurora. Aurora gets a slightly bad rap as being a lessor place, becuase there is a lot of indutrial space there, Bucky AFB is there and all the cool hipster stuff in down town. But friends I had in the area really liked it. Live in the right place and it solid blue collar honest folks.
Now the flip side of being pricier, is there is a ton of cool stuff to do for almost nothing. Red Rock colloseum, when not a concert venue is a state park, free entry and is strking in its beauty. If you are into bicycles, there are a dozen trails around the city, road bikes; there are great roads; off-road, a dozen trails; hiking, 10 minutes and the trails are everywhere. Hell, just hop in the car and find a squiggly line on the map, there are hundreds. There are a dozen cool festivals, parades, neighborhood parties and events every month in Denver or in one of the towns around Colorado.
The tracks are good. High Plains raceway is about 45 minutes east, is huge and very new. Lacking in facilites but they are getting better. Pueblo is just down I-25 a little under 2 hours. Its older, a muli-use facility but has a great family run atmosphere I always loved. I never made it to La Juanta, but its an old SAC runway converted to car use, and Hastings in a few hours northeast in Nebraksa. Car and bike culture is huge there, there is very little rust, but I think Denver may still require emissions testing. Vehicle registrartion is priceir than I was used to in OK, and a bit of a PITA, but not quite to California levels I am told.
If you like beer, you will love it there. Micro brews everywhere, and the Denver Beer festival every year.
I think your missus can get started sooner than she thinks is hair. IIRC Oklahoma actually has some pretty serious guidelines for beauticians and Colorado may readily accept them. I would look into it. a liscenced beuatician is always going to be in demand, she may not have th repaet business right away, but if she has built clientele in OK, then she can do the same in Denver. Good business is always good business.
I would suggest an extended weekend to visit, get a good solid assesment of living conditions, prices and impressions. Who knows, you might convince her. Next month would be a great time, as the Aspens will start to turn soon and its a sight to behold.
It's a days drive from Tulsa without even trying that hard (Western Kansas is the most boring drive in the world, worst than the Dakotas and West Texas, don't you dare speed, becuase they are brutal), and priceline a decent hotel you could probably do it cheap during the week (I would presume her weekends are quite busy)
Good luck.