Yet another vote for adaptive drive. I have a 35d+adaptive and I really like it.

I'm considering trading my x5 for an x6 and spent this weekend driving ones with and without the sport package (hence adaptive drive). I Really wanted to be able to get away with not spending the extra $4600. I found that if you're used to adaptive drive, anything less is not acceptable (kinda like the multi-contour seat issue).

I think if you get it you won't regret it. Get it, and then to make yourself really happy that you did, go back to the dealer after you've had the car for four months and drive an x5 without it. You'll be glad to get back to your own car!