Just off the top of my head--please correct my mistakes. We have several teams dedicated almost exclusively to the spread. It's just not necessarily the teams who are competing for the championship. That said, most everyone uses multiple sets--Ohio State had an unholy spread attack in 2006, for instance. The teams with deeper talent tend to run a bit of everything successfully, but the bread and butter is a more traditional style offense.
Iowa (Pro set)
Minnesota (Pro set)
Wisconsin (power all the way--and it's beautiful)
Illinois (Spread)
Northwestern (Spread)
Indiana (Spread)
Purdue (Spread)
Michigan State (Multiple Sets)
Michigan (Spread)
Ohio State (multiple sets, includes spread/option)
Penn State (ditto)
The trick with the big ten is that you have to be able to defend, well... everything. In a league that emphasizes defense, the scores tend to be lower and the margin for error is slimmer. You can't have a weakness on defense, or there's a team out there that will exploit it.