Whichever way has the best things to see!
Thanks for responding!
We're pretty open and can allocate up to 2 or 3 days for the trip. We were thinking of heading up through Pennsylvania, the west across Ohio and Indiana. So in terms of highways, I guess I-70, I-76, I-80 and I-90 - which is just the most direct route that I found online. But we'd be open to trying a slightly different route if there's cool stuff to see.
If You're Looking for Fun
Along America's North Coast, between Cleveland and Toledo, in Ohio, is an island in Lake Erie referred to as Put-in-Bay (actually on South Bass Island). If you're looking for a party like in Key West, this would be the place. The magnificent Perry Peace Monument is there as well. It commemorates the War of 1812's Battle of Lake Erie which took place nearby. "We have met the enemy, and they are ours."
Also, in Toledo, you have to stop at the original Tony Packo's for a hotdog like you've never had. This place was featured on two MASH episodes.
Keep on Down that Two Lane Highway. --RoadDog