Re: Boat Length?
My brother just bought a 2002 Triton TR21 with a 225 Mercury Optimax. That is one sweet ride. It takes some time getting use to the handling once it gets to 65+ mph but once you get a feel for it it's fine. Will do about 74 mph. I personally wouldn't get a boat under 18' but depending on where your fishing... it may not matter too much. My brother and I tournament fish and on places like the Potomac River it can get pretty rough. A bigger boat won't beat you up as bad.
He was going to get a Bass Cat but got a GREAT deal on the Triton plus the Triton is a lot wider than the Cat. As far as motors go... wouldn't buy anything but a MERC! Hope you get a good one! Good luck.
Eric