Most of this question has already been answered by NDSU92 and student, but I'll sum it up and add a bit.
The philosophy GT follows is to schedule FBS games that benefit our program the most. The benefit is two pronged: money and fanbase. The game has to be worth enough to offset a potential seventh home game. Since the profit on home games is north of $250k, we generally require $300k or more for FBS games. Not many MAC, SBC, or CUSA schools can afford that. The other prong is fanbase. We want games in our region so that at least a couple thousand of our hard-core fans can make the trek, and the rest of the fanbase stays interested in the game because it's a name they recognize. That narrows the field to B1G, Big 12, and eastern MWC teams. There's also the factor that the game should be winnable. At the very least, there shouldn't be a huge risk of being embarrassed on the field. Don't expect Alabama or Oregon on the schedule anytime soon. Maybe we'll push that envelop from time to time, but that's the basic format.
Let's use a couple recent-ish games from us and the school up north to compare. For our Kansas game, it was a relatively easy drive for us. That allowed a strong contingent to drive down with their tailgating rigs. More flew in. It was a name school, so we got the game on TV plus our fanbase found it easy to buy in. Kansas is rarely a powerhouse, so we were safe from a potential blowout. Now consider UN_'s game versus Texas Tech a few years back and why we wouldn't have scheduled it. At the time, we wouldn't have matched up well with them; a blowout would not have been out of the question(UN_ did a pretty good job not getting totally destroyed - kudos). The much bigger factors were that TT doesn't have a great media contract(the game wasn't on TV) and it would've been too far for a large Bison contingent to make the trek by car. Most of the ones that made it would've had to fly and leave their rigs at home. And the money wasn't great. TT paid $300k at the very most, and it might have been a little less. It wasn't a bad game for UN_ to take, but it was just outside the parameters for what we're looking for.
In case anyone is interested in booking anything that will let them, the NCAA has announced the FCS Championship will be in Frisco on January 10, 2015 along with the first College Football Playoff title game on January 12, 2015 in Arlington. Per Dom's twitter account.
Dom Izzo @DomIzzoWDAY 18h
College Football Playoff 1st title game set for January 12, 2015 in Arlington; #FCS goes January 10 in Frisco;2 title games a half hour away
Unofficial Official President and Charter Member of the Paul Miller "Miller Time" Fan Club
If you leave tailgating hungry and thirsty, you're doing it wrong
I am so sick of the Bison already. Win this, win that, blah, blah, blah. I'd really, really like to know how they do it. I swear they have to be the luckiest sob's on the planet. Just sick of this bs, just fed up.