I've always flown to Ohio when visiting people.
Once there we usually rented a car. It's easy to drive around the cities and outlying towns, and there is nowhere near as much traffic as there is in Los Angeles.
When travelling to Columbus, we chose to take I-70 Westbound from Pennsylvania. There were a few construction areas, but no delays > than 5 minutes.
Columbus has an excellent hoghway system in & around the city & we found it easy to get around. All signs were well marked.
unless you are staying on campus i would definitely recommend having a car, or renting a car. public transit here is not that great so you probably won't have to much to do w/out a car.