As far as the 330 and A4, I'd definitely recommend them.
As far as the GTO goes, of course I'd recommend that. I got mine, an '06, with 13,000 miles for $14,500. It's a fantastic car, and I love it in every way. I've only put 7,000 miles on it, but it's comfortable, easy to drive, and hasn't given me any problems. I took it all the way to Canada from NC and didn't have any problems with the comfort. It's a solid car. Also, I've taken it to the track (Virginia International Raceway) twice already and the thing performs quite well. The only reason I didn't recommend that was because it's a 2-door.
You were asking about the RX-8 - I don't know about its reliability but the rotary engines in the RX-7s were REALLY unreliable. So I don't think I'd touch a rotary, but maybe the new ones are better.
If I were you, I'd go for the manual 330, A4, or G8GT (but you'll need about $18,000 for that at 50,000 miles). Good luck.