Anddd here comes the sport bike vs. cruiser argument in 3...
Anyway, OP, get a bike. Sport bike, cruiser, chopper, whatever the hell suits your fancy. They're a hell of a lot of fun and you can ride them any time the weather is nice and you have gas. Keep in mind that if you get a bike you'll have to look at insurance, as well as buy things like a helmet and leathers, which can get pricey if you want good stuff.