Danielle, as you might have figured, your original request was a little vague...within 8 hours you have roughly 40-50% of all the amusement parks in the country. Can you narrow it down a little? Personally, I'd recommend spending some time in PA, some fantastic smaller parks there as well as some of the medium-sized *chain* parks.
bill, noticing that "all the ones in CT" isn't really putting in a lot of travel compared to some...
The problem with this kind of thread is that everyone has a different opinion of what a "great park" is. Unless CtCoaster can be more specific in what he/she is looking for none of us is gonna be of any help [well, except for Gonch's excellent reply].
CP, Kennywood (cant believe no one has mentioned this one yet,) BGW and Hersheypark are among the gold standards for amusment parks in this country and have loads of coasters I highly suggest visiting them.
Also, consider this, if you buy a Six Flags pass you can get into SFNE, SFGAdv, SFDL, and SFA for free and they are all within driving distance of your home.
Driving at 65 mph, I count 126 parks within 8 hours while staying within the US. Of those parks, here are the biggest/most popular/most talked about (sorted by nearest to furthest):
-SFNE -Great Escape -SFGAdv -Knoebels -Hershey Park -SFA -SFDL -PKD -BGW -Kennywood -Cedar Point
Of course the last couple may be over 8 hours, my calculations only pulled in all parks within 520 miles (8 hours at 65 mph), but that is by way the crow flies, not actual driving times. I'd say check out all their park websites, decide how far you're REALLY willing to drive and go from there. Another thing is how much you're willing to dpend and how long you are going. If you have a SF season pass, you could probably hit SFNE, GE, SFGAdv, and SFA right down the East Coast. All depends on what you're looking for...
She wasn't specific...typically that is the problem with questions like this. If we're not told specifically who is on the trip and what kind of experience they're looking for all you're going to get is people responding with a suggestion to visit parks THEY enjoy.
If someone hopes to average 65 mph driving in the NE, they better plan to go around PA-- the orange cone capital of the world-- state mottoes "Single Lane Ahead," and "Road Construction Next (fill in blank) Miles."