One of the now defunct parks that did that was West View. Check out the long thread on that park. Those Flying Scooters were awesome, the Whip was one of the best around, the bumper cars were classic Lusse cars, the Trabant ran both forward and backward, the Paratrooper turned quickly, the Tumble Bug gave a nice kick of airtime on the first dip and allowed you to slide all over the place, and the Caterpillar had its cover and fan. The flat ride cycles were usually long. Of course there were those great coasters and darkrides as well.
If you miss West View, you might want to make the trip 250 miles east to Knoebels. It's a park a lot like West View but in a more beautiful setting.
I'm glad someone mentioned Indiana Beach. Their "Flying Bobs" go on for what seems like forever. The cycle is twice as long as the Matterhorn at CP, and then they run the whole thing backwards, just as long. I don't know this for a fact, but you have to be on that ride for close to 4 minutes.
Waldameer does have some of West View's essence but lacks the big wooden coasters at present. CLP had some of West View's character as well with Blue Streak (same builders as the Dips) and a number of flat and kiddie rides that were once at West View or were similar to rides that were at West View. Had they opened, they were planning to put in a darkride that came from there as well.
Kennywood, has by far the longest ride times on their flats that I can recall (Ive been to Knobles but dont remember their ride length) while KW's rides may be mostly classic (and thus incapable of going on "berserker mode") the newer ones certainly do.
One of the important things about KW is that they have a great selection of thrilling flats. That Enterprise (AKA Volcano) is one of the best with the ride going almost completely vertical and the cycle being of decent length.
Cosmic Chaos has been a big hit this year and the park is probably having second thoughts about not using the bigger disk instead of the 24 rider version.
It's not Six Flags. I'll tell you that. No tilting Yo-Yo's, boring Huss Top Spins, and short cycles on the Huss Frisbee. Even the Huss Breakdance is a bore. I'm not saying that all there flat rides are boring, but it's a Breakdance. Those rides are supposed to be intense. I'm talking about the one from SFOT.