SLC, I'd like to welcome you to OKC. I am an expat but was born and raised there, and still follow development and am a huge booster of the renaissance taking place.
If you'd like a more intimate OKC discussion, there are OKC centric forums that discuss development and city life in more detail (Ill let you google it, haha so not to disappoint SSP).
But yes, OKC is booming and has been rather organic for the past 15 years or so. I personally prefer OKC to SLC (I've been, but did not care for the ultra conservative nature) for most things other than your mountains which OKC doesn't have.
As for nightlife, OKC is more of a very big college city in atmosphere that is slowly but surely emerging as a major US city. One thing that I love about OKC now is the pride that people NOW have in their city.
Again, if you're serious about moving - I don't think you will make a mistake. The price is right (you can live right in or near downtown for very inexpensive) and yet be in the middle of all of the action.
And yes, we're all excited about Devon Tower - because this is being built during the recession; we're all hoping for a HUGE explosion (for OKC anyways) once the recession is over.