2009: 27/ 01 Car Hire, Geneva
Snowheads is a constant source of good information, and here is a link to a thread regarding car-hire at Geneva airport.
From personal experience I will say that the new system whereby you get a minibus to the car-park from the rental area is fine for your first time, BUT in fact it is only about 200 yards.
So if there is a queue, and your bags have got wheels, it really is only 5 minutes walk. Ask at any of the desks and they'll point you in the right direction.
