I'm definitely getting the Wii version. Just holding out on pre-ordering until I find out what the bonuses are (if there are any).
Lightcycles on the PC version sounds like it would be painful with no gamepad support. Driving vehicles with non-analog controllers is never fun.
When you drive your car, do you turn the steering wheel as far to the left or right as possible when turning? Because that's what driving a vehicle with a keyboard is.
Luckily, I have a N64 to USB converter, so I'm good to go if I get the PC version.