1. Limited-Slip
2. Sport seats. Not necessarily Recaro (though it'd be nice), but a well designed bucket seat with good bolstering and cloth and leather options. If Chevy can do it with the Cobalt SS (best seats I've ever been in), Toyota can do it
3. Sunroof. It may sound poser-like, but a good sunroof is a must for me after having owned my Mazda. I love it and it lets my stoner buddy smoke in the car and not bother me with the window noise or smoke. HAHA
4. Good brakes. Not just 4-wheel discs. A great set of calipers goes a long way. They can borrow them from the STI parts bin (WRX brakes suck in the cars I've driven.) I'd pay extra for STI brakes as an option so I don't have to do an full aftermarket upgrade later.
5. Traction Control OFF. The ability to full remove TC is on many American cars. Its on my Saturn Ion sedan 5-speed LE5. I love it cuz it used to be turbo and would light tires up into 3rd. I can turn it off on my Mazda6S. its wonderful chucking it into a canyon and feeling those tires claw for grip.
6. Race/Track pack. You can get all your cool navigation and MP3 touchscreen gadgetry in a package. Give me a track pack akin to the Gen Coupe with less crap. Hyundai did something wonderful by designing the 3.8 Race-Pack and 3.8 Track-Pack.
7. Optional stereo that is NOT Bose. As an audiophile, I am appalled that these companies go with Bose for cars. Give me eminence drivers with nice horns.
Really, a decent stereo AS AN OPTION would be nice. I'm too old to upgrade, but want to hear my 90s tunes in clarity as I hoon the hell out of it on the back roads.
8. Launch Control/No Lift Shift. The Cobalt SS has it and its so easy to use. Perfect launches every time and the quarter mile was nearly a second different with the NLS on vs off. While best used for turbos, even on my NA car, my N2MB makes a huge difference.
9. Synchro-rev matching. Not hard int he grand scheme of things. It'll probably not happen on this car, though I could see the new Supra heading that direction.