In addition to xenons (ugh...PLEASE!), I would happily pay for Keyless Go.
My Prius and my Mazda both have this feature, and it's really something that's difficult to live without once you're used to it. It's similar to getting used to keyless entry and then using a car where you have to insert the stupid key in the door, open it, and use the power lock button to let your friends in. Not the biggest deal in the world, but a great small luxury.
Steering wheel audio controls will also be very difficult to give up. As it is now, I can adjust volume, choose a source, and flip tracks on my iPod without ever having my hands leave the wheel.
-Drew