LaCrosse is a beautiful, reliable, pampering friend of mine. This car quickly became a new 'member of the family' if you will. I love how it just takes care of me. It is very quiet, comfortable, it behaves well on the road (it does not float the way oldie Buicks used to but it won't treat you to a nasty choppy ride either) and it is very safe (tested great on the government crash tests). Plus, you have added security and convenience of OnStar, XM radio, handsfree phone right on the steering wheel. I even found a comfy seat setting for my back - something that didn't quite happen even in Audi A6. The steering is just right, not too hard, not too wiggly and it adjusts to your speed.
I am short (5'6"), so the ultrasonic rear park assist is a must on any future car. That'll be easy, though, since it will likely be another LaCrosse. Remote start of LaCrosse: a must for a hot climate. Start the car remotely while indoors (office, restaurant) and it cools itself before you get in.
Not anything pressing. Maybe the compass could be on the rear-view mirror, rather than on the dash.