Personally, I prefer the G35 over the 350Z. I like the looks of the G better, although the updates for '06 to the 350 have made it look quite a bit better and more upscale. The interior of the G is also better then the 350, which is kinda cheap feeling for a $30K car. The cars preform very well, and the ride isn't too harsh considering how tight the cars are (keep in mind that I drive a truck with all of 1" of suspension travel and no shocks, and don't think it has a harsh ride either). There is no shortage of aftermarket for either, although the 350Z gets more stuff over here.
I'm in the market for a RWD coupe as well, but I'm not even considering the G 35/0 Z, not because they aren't good cars, but rather they are way, way too popular around here.