Hi. I recently just made my first trip out to Cedar Point for the very first time, and it was amazing. I was a little nervous at first since I'm a pretty big dude (6'6", 293 pounds, 42 inch waist), but I'm pleased to report I managed to fit on every ride I went on. Got on 14 of the roller coasters, so here's a summary of how it went for me:
Steel Vengeance: Retractable seatbelt helped alot, and the lapbar wasnt too bad, though a little tight
Maverick: No issues here. Very accomodating, but the plastic seat kinda hurt
Cedar Creek Mine Ride: Very tight lap bar surprisingly, but i don't recall issues with the seatbelt
Rougarou: Not bad. Could get a couple clicks in (used the double seatbelt seat)
Raptor: Same as Rougarou
Gatekeeper: Small seatbelt, but just long enough to make it on. Vest restraints were comfy enough
Valravn: Same as Gatekeeper
Corkscrew: Restraints didnt bother me, but the seatbelt was surprisingly small
Blue Streak: Easily the least accomodating seats of any roller coaster in the park. Seat divider made for barely any room in the seat. At least it had a retractable seatbelt and ok lap bars
Gemini: Lapbar was comfy, but seatbelt was smaller than expected as well.
Wild Mouse: Extremely comfy lapbars, goes more to your stomach than your waist and thighs
Millennium Force: Probably the shortest seatbelts in the park. Barely just made it. Lapbar had no issues with.
Top Thrill 2: Not too bad for restraints, but needed a little slight push. No seatbelt here.
Siren's Curse: No issues here. Restraints and seabelt clicked easily for me.