I am not terribly big myself (size 10-12ish) but I have a very good friend who is quite large and he does not like CP very much due to its roller coasters not being er... big person friendly.
The new coaster Maverick, has over the shoulder restraints, with that in mind, it is VERY accommodating and is a spectacular thrill ride, definitely one not to miss.
Blue Streak, Millennium Force, Raptor and Top Thrill Dragster are NOT big person friendly. Blue Streak is a wooden coaster, with a seat divider and a very short seat belt. Millenium Force and Top Thrill are both Intamin Rides, they have a seat belt/lap bar restraint, that used to be more accommodating now it is as far from as possible. About two years ago, after the Six Flags Superman accident (guy was WAY to big to be riding) Intamin came out with a recommendation for seat belts to be shortened to a certain length. As CP is in Ohio and Ohio is a state that requires Amusement Parks to follow any recommendation by a amusement ride manufacturer they were required by law to shorten the seat belts on their two Intamin roller coasters, Millennium Force and Top Thrill.
Now not only does the seat belt have to fit, but you have to have atleast 1-2" of slack on it (the length is debatable depending on the ride attendant you get) My Husband who is 6'4" 230 pounds size 38 waist could barely ride Millennium Force and Top Thrill.
Raptor is a B&M, also European (both Intamin and B&M are European based companies) is world renowned for not being accommodating, Raptor was the world's third inverted coaster, and they hadn't yet come out with the big boy seats (that's literally the technical term folks!).
Now... you should have no problems with Gemini, Corkscrew, or Magnum XL, all Arrow coasters BTW an American company that went under about five years ago that was known for being very accommodating. So sad.
Overall though CP is a park I think anyone who even has a remote interest in amusement parks should visit, it is the mecca of amusement parks quite literally and while it has 17 coasters it has MANY MANY other attractions as well. Enjoy your trip.
Jennifer