I would also recommend a Garmin: there are many models but you can have hours of entertainment (or pain depending how you look at it) reading user reviews on Amazon or elsewhere. It actually encourages a more "off-piste" driving style having a sat-nav as once the destination is set it will always re-calculate a route when some road catches your eye and you take a detour. Some argue that you don't learn where you are because you just follow the pink road and there is some truth in that, but the upside is that those er.. discussions.. don't happen in the same way anymore! Now you just both blame the sat-nav when things go wrong.. Our is called Mercedes for some reason...
I would recommend a "shot bag" holder as it will go nicely on the gearbox tunnel just in front of the gearstick..
Route Planning is best done using Google Maps and Google Earth in my opinion, and then manually transferring the waypoints to the sat-nav. There are ways to interface the two, but good luck with that.. it's a lot quicker to just enter the places into the "trip planner" as it is called in Garmin. Actually a good old fashioned MAP still works best for planning..
Have a lovely trip.
Oliver S.
