I generally don't bother with big water, and I'm looking pretty seriously into one of these-
Outdoorsman ModelIndian River Canoe
which will ride atop a car, and do about 18mph with one of these-
Honda BF2 Outboard Engine - 2 hp boat motor specs and features
And goes for about $1400 total. A buddy has one set up with a tiller extension so he can run it standing in the middle to spot fish. Makes a feller envious when he's covering 5x the area you can while paddling a kayak.