If you can get past the quirkiness of the RX-8, it is a pretty cool car. My old roommate had one and he said it was very enjoyable to drive around town (it did need some revs to get moving) and was very capable on the track. The rear is surprisingly roomy, sort of like a compact sedan. I sat back there plenty of times and as a 6' guy I never felt cramped.
Otherwise I would say go for a G35/G37. Good strong motor, nice interior, and available with 6MT. It's basically a 350Z/370Z sedan. Also very capable.