Well, we got Platinum Passes for Cedar Fair parks which only coast about $180 and got us into the three major parks for as many days as we wanted with free parking, early admission, discounts on food and merchandise. No doubt the way to go. Every park was amazing. The only one i had been to prior was Silverwood which is a small amusement park in Idaho. Note: they have a very unique coaster there named Tremors that goes subterranean at least 4 times, maybe 5. Driving in between was exhausting but we made due. Valleyfair i had never heard of but was way better than i could have ever imagined. Note: check out Renegade. We stayed there for most of one day. King's Island, considering it is one of the biggies in terms of amusement parks was somewhat of a letdown, but I think it was more because my friend had been there so many times that he wasn't as hyped as I was. Still had some world-class rides (Diamondback, FireHawk, The Beast [definitely not a let-down, though sadly no Son of Beast], Flight of Fear, and a great river rapids ride). Cedar Point, obviously the best of the best. Millennium Force was no doubt my favorite, but Maverick and TTD were great as well. Long lines (2-3 hours), hot weather (100+), and lots of water...most fun I have ever had in my life. The best park about Cedar Point is that every coaster there would be the main attraction at another park so I was thoroughly impressed by everything even though I knew it would be amazing long before setting foot in the park. Note: other great coasters at Cedar Point include Mantis, Magnum XL-200, and Raptor Note: Disaster Transport, while seeming lame, is very unique in that it is a free-moving bobsled/flying turns style coaster
If you have any more questions, ask away! :--D