cedar point is a must
www.cedarpoint.com
from there you could head south towards cincinatti and hit kings island (another amusement park)......and west virgina area has some cool carverns and such.
my favorite spot on the east coast is wilmington north carolina (cape fear), the downtown area is very historic.....the beaches are awesome and it's not super touristy like mertle beach.....there you can tour the uss north carolina (decommisioned battleship), also a nice aquarium.....
it's also one of the areas where giant tortises come ashore to lay eggs (springtime).
have more info if interested.