rob, a good fast boat to start with would be something like the Graupner Salinas, its 2ft long, and about 10 inches wide, and is styled like one of these half million pound sunseekers.
My first boat was a Robbe Najade. too much vac form and vague instructions, however it goes well once its built, and its "starwars scale", in other words, those 3.75inch figures that you can buy in toys-R-us are pretty much in scale. I wanted Lara Croft and Indianna Jones for mine, but Hans Solo and Aura Sing it ended up being.
Whats everyones preference?
mine is for scale working ships, hence 2x Graupner neptun's, a modified Sydney Star (which are a hoot to build as long as you use Robbe rudders), 2x tug boats (one of which is an RTR, the other I got ready built but is a kit) and an e-bay lash-up that went from supply ship to survey ship