I've had my RX300-SE for a couple of months now and have to say I'm more than happy with it. Plus points far out-weigh the negatives. If I could change anything it would be (all petty and in no particular order):
Audible alert when alarm is activated/deactivated would be useful.
Climate control could be more flexible, I would like to have the car at a certain temp without having my hands/face frozen by the face level vent.
Driver should be able to control all windows even when disable window button is pressed.
I'd prefer a handbrake to a foot operated parking brake, more useful for steep hill starts.
I'd also like a visual indication of current gear when in drive, I'm still not totally used to an automatic and often kick down too aggressively and end up with the engine screaming like a banshee.
Rearview mirror included in the wing mirror and seat memory.
Oh, and It would have been nice to get ICE and Sat Nav thrown in for free :P
So what's on your wishlist?