J.R.
I lived in Nashville for about 4 years. Clarksville is about 45 min to 1 hour north of Nashville. It is rolling hill country, very green and humid. Summers are hot and humid, winters are mild with occassional snow and ice storms. Clarksville is near Fort Campbell, there are a lot of military personnel who live there.
As for Middle TN - I love it, we've considered moving back. Living near Nashville is great. The city has all kinds of things to do, the obvious - music, lakes, several Universities and Colleges, hiking and camping. Middle TN is also "close " to so may other parts of the country, if you like to travel it's easy to make weekend trips to the midwest and south (ST Louis and Cincinnati are about 5 hours, Louisville 2-3, Birmingham 3, Smokey MNTS 4).
Housing is less expensive than in Colorado, I don't know about Utah. Clarksville is less expensive than Metro Nashville. I would visit the Chamber of Commerce website and Realtor.com for more info.
Good Luck, if you end up there you should find it's a great place to raise a family.