I’m in a small town on the other side of Nashville. If you do move here, we should have another middle Tennessee Dopefest to welcome you. 
Back to the question. IME, you’ll be close enough to Nashville to go to cultural events and the like. My small town (Lebanon) is pretty agriculture oriented, but close enough to the city that many of us commute (we have commuter rail service from N’Ville). And Comumbia isn’t an hour and a half…more like forty-five minutes.
I’m not sure what you’ll find in the GLBTQ community in Columbia, but some small towns with art, music or tourist based economies do have a few urban ex-pats. Otherwise, you may be more comfortable living closer to the city.
A lot of folks only know Nashville as a country music center, but you’ll find all kinds of entertainment here, from the street fairs on Jefferson Street, the International festival in the south part of town, a few good blues bars, a couple of jazz clubs, alternative theatre, a reasonably good symphony, ballet, rep theatre and opera. It has also changed greatly from the town that twenty years ago had very few ethnic restaurants (besides barbeque and meat and three, which, by the way, are good enough to gain some serious weight on
) to the current melange of decent Mexican, El Salvadoran, Persian, Ethiopian, Cuban, Creole, Greek, Lao, Thai, Vietnamese…well you get the picture. If you like sports, there’s the Titans, the Preds and the Sounds.
You have to look harder for variety in the small towns though. A lot of life seems to revolve around church, high school football and the local eateries / watering holes.
If you get involved with some community endeavors, folks will usually come to accept you, even if your lifestyle differs from the local norm. I’ve learned to accept the “Have a bless-ed day!” thing with a “You too!” for the most part, heathen that I am. I’ve also learned to put my foot down when the whole evangelistic thought train goes over the line.
You’ll likely find that life moves at a slower pace here. If you’re a person that needs constant action, you’ll probably die of boredom. If not, then you’ll be in hog heaven.
I can only speak from my middle aged, straight, no school kids, Yankee, agnostic, single woman’s perspective, so take this with a grain of salt.