I think a small-scale Eurofighter like Hydrus or Adrenaline Peak would work wonders here. It has low capacity, a very compact layout, and also it packs in a ton of elements that would be unique to the park. Cedar Fair has worked with Gerstlauer in the past half decade on Hangtime at Knott's, so...
Including relocations, I have ridden:
Ragin Cajun at Six Flags Great America
Avalanche at Timber Falls
Both Avalanche and Firehawk I went on during their last year of operation.
EDIT: Oh right, I completely forgot about Apocalypse at Six Flags America...
OK time for an update, I've visited 3 new states in terms of credits after my last trip, so here goes:
California: X2, Six Flags Magic Mountain
Florida: Kumba, Busch Gardens Tampa
Georgia: Goliath, Six Flags over Georgia
Illinois: Goliath, Six Flags Great America
Indiana: The Voyage, Holiday...
I guess I'll throw my hand into this little game, here goes
North America: I've done most of the major coasters in the USA so I'm gonna say MindBender at Galaxyland in Edmonton. It's the tallest indoor coaster on the continent and also the most intense.
South America: Katapul, it's a...
Probably Michigan's Adventure last year. It was so empty and quiet it was kind of sad, granted we were at the park pretty late. I was also literally the only person on Thunderhawk (my second ride on it) and it had a breakdown while I was sitting at the brake run.
The only one I really am not sure about is Barnstormer at Magic Kingdom. I think I remember riding it, but I don't even remember. There's not even photo evidence of me on it, same with Shamu Express and Journey to Atlantis at SeaWorld Orlando, but I remember writing a diary thing on my trip back...
Bay Beach Amusement Park. For one it's the closest park to me so I go at least once a year and for two the individual ride tickets are super cheap, 1 ticket is 25 cents, 2 is 50, and so on and so forth.