I agree with Cedar Point. If you are a coaster enthusiast, this is your Mecca. Not to mention that Cedar Point has a storied history from 1870 to now, is home to the first 200, 300, and 400 foot tall rollercoasters, as well as several firsts in the coaster community including Steel Vengeance as the first hyper hybrid.
Disneyland would be on the list for sure, due to this being Walt Disney's original baby and the historic attractions such as Matterhorn Bobsleds which is an ACE Coaster Landmark if I am not mistaken. If I recall, early on in Disneyland's history, Walt Disney had a stake in Arrow, which is historic in the amusement industry as well.
I want to add Walt Disney World to this as well, as it opened 16 years after the original Disneyland in Anaheim. If you haven't read the story on how Walt Disney acquired the land for the "Florida Project" it's pretty neat. Also, the infrastructure within the resort, particularly the Utilidors are interesting. What's interesting about all of this is how Walt used Disneyland in the 1950's as a learning opportunity for building in Florida.
If you are a fan of the carnival games, I want to give a nod to Indiana Beach, for their Fascination game. Out of all of the parks I've been to over the years, this is the only park that I've been to that has this game, but supposedly Kings Island and Cedar Point had theirs back in the day.
Rivertown River above mentioned Six Flags Great Adventure (or if you've been here awhile, NJFTP as Terpy likes to call it) in their list and I would have to agree. They have the tallest coaster in the World here, one of my most favorite wood coasters, El Toro, and one of the first B&M hypercoasters in Nitro. Seriously, a front row ride on El Toro is something you have to experience due to the insane ejector air. Plus, it's the only Intamin pre-fab woodie in the U.S.