If you really are looking to trade, I'd say look at a 2007 G35 Coupe MT. They had over 300 hp and are a blast to drive. You can also pick one up for a tad bit over $30,000. They are new enough to still have a warranty and not too expensive to maintain. You also get a nice cushy interior with all the goodies, Navi, blue tooth, Bose stereo system as well as some usable rear seats. Not to mention the trunk space.
If you want something a little more exotic, then what about an E46 (2002 - 2004) BMW M3? (333 hp) I owned a 2002 convertible for a while and they were a blast to drive. Torque for days. You got all the power at 2,xxxx RPM's. It was fast and the most stable car I have ever driven at high speeds. I guess because it weighed almost 3800 lbs. I could hit 140 in that car and lean back like I was doing 75. You can get a clean one for the high $20k's. Again, you can find one with all the goodies, Navi, xenon, BT, upgraded stereo, etc. It has a good backseat and good trunk space. It also will get attention, althought not like the NSX. But if you're looking for a terrific driving experience, then that car is definately recommended. The up keep will cost you though and it is a little older that the G35 Coupe.
Other than that, you can do a new Evo X or STI but they are so...