It's interesting to see how different people experience things differently, and also value things differently. The first ATS that I encountered was a Premium at a preview at a local mall. Sitting in it, I was amazed that the seats were so comfortable, both front and rear. I didn't think the "sport" seats were particularly sporty, but they were very comfortable to me. My next encounter was with a loaner ATS 2.5 Luxury, which I had for about a week. Though the seats looked the same, or at least very similar, to me they felt flat and unsupportive, and just not that comfortable, no matter how much I fiddled with the controls. I noticed also that the headlights pretty much sucked, especially on the high-beams, and I didn't realize it had no LEDs until I saw a reflection, and felt kind of ripped off! I was pleasantly surprised by the excellent handling and grip of the base suspension, but also surprised by the occasional harshness of the ride, which was worse than the ride of my CTS-V when in sport mode. This was on 17s, too. I also got to play with the sunroof, and found it too small and too noisy to be useful, and played with the CUE and Nav, which I overall liked.
When shopping for my own car, I checked out the Performance and the Premium, specifically with regard to the seats, lights, and ride and handling. I checked out the HIDs at night, and they were definitely better (though still not as good as the ones in the CTS, IMO). I found the seats again to be superior in comfort, just as I remembered. And the ride in the Premium when set in Tour mode was indeed less harsh and more supple, while having even more grip. I didn't really have to have the HUD or the driver awareness package, but I thought the suspension, seats, and lighting more than justified the extra cost. The other equipment was basically an added bonus. Now that I have lived with the car, I think the driver awareness package is really useful, and it has saved my ass a few times. One does have to get used to it though. One nice thing about the seat alert is that your passengers are unaware of the alerts. In any event, as I would have bought the Nav and Bose upgrade, the 18s, and the cold weather package at a minimum, the difference was only about $3k, or about 6.5% of the total. I don't think that's a lot for all of the upgrades that the Premium offers, especially for a luxury sport sedan, but to each his own.
To honest, I could have lived just fine without the leather and wood. If I could have ordered the suspension, seats, and lighting separately as on the BMW, I could have saved a few thousand bucks. That's not an option on the ATS, though, and so equipped, a 328 Sport would have been the same price as my loaded ATS Premium anyway, so it's still a great deal, as well as a great car.