If the restraints are really tight, then I'd like a short ride. If the restraints aren't tight, then I'd like a long ride. If the ride is repetitive, I'd like a short ride. If the ride spins way too much (I'm looking at you, Megaspin), I USUALLY like a short ride.
And if the ride has lap bars, isn't repetitive and doesn't spin too much, I like really long rides.