The Steamin Deamon @ the Great Escape about a month into the Season...
I would say that the roughest i have ridden is probably either vortex or OL:FOF (wiht horsecollar). Oh and SOB is awsome this year just like last. When i was at PKI last saturday i found the seat that gave the smoothest ride. First car, second seat. Trust me on this one.
Batman The Escape stand up at Astroworld. This is the worst coaster I have ever ridden. It really hurts, not just "a little" rough. It HURTS.