The best advice I can give you is BEFORE lining up for rides like Superman or Green Lantern at movie world is speaking to the entry host and asking if you can test the seat before lining up. That way it saves you the embarrassment if you are unable to fit on the ride and wasting time lining up.
As far as Scooby Doo goes, it's very odd with regards to larger guests. However I can suggest sitting in the back row of the car as there is more legroom which makes it easier to spread out if required. Batwing the harness does NOT need to touch you, as long as the seatbelt is done up you will be OK to ride. Superman will require all 3 safety checks to pass, which includes being able to see a yellow line of stitching on the seatbelt, the lap-bar touching your legs and making sure you can move side to side in the seat comfortably.
Wild West Falls is also pretty accommodating, but once again each seat / lap bar is ever so slightly different but if your unsure if you will fit i'd suggest riding in your own row to ensure the most likely success. One last tip with scoobs, if you have any bags either leave them in a locker or have someone else riding with you place them between your feet to give you the most room possible. If you have any further questions about Scooby, Batwing, Wild West Falls or Superman restrictions please feel free to PM me and i'll try my best to help out...