I've owned an Audi, a BMW, and a Lexus. None of those satisfy me like the STS Northstar. It has lots of power, the best handling sedan I've driven, PERFECT Audio by Bose, great engine tone, and luxurious appointments. I drive nearly 80 miles every day so comfort and fun are important to me. None of my previous luxury cars have held up well. My Corvette is still my weekend car though. I am thrilled with this car, but when the time comes, I'd love to get an XLR-V (yeah, I just need to save for 2 years :-D). I suggest you stop looking after Cadillac. No BMW, Audi, or Lexus will compare, and I have experience with them all.
The Bose 14 speaker audio, Northstar V8, Headlamps, A/C, clean looking guages are so, and beautiful leather and wood trim.
Give it more front passenger leg room (the glove box is huge. My only found flaw)