Same Arlington TX factory, same personnel, same parts aside from those that need to be different cosmetically or to provide functionality GM wants to offer exclusively in the Denali or Escalade. The MMI in the Escalade is brand-specific to be consistent with other Cadillacs, though it's probably not as good as the MyLink MMI.
I had 3 BMWs in a row before this Tahoe, and my wife has a Mercedes C300 now. I won't lie, the quality of interior materials is superior in those. Not as much as it used to be though, and my sense is that the Tahoe is as good a full-size SUV as the BMWs were good sport sedans. It does what it is supposed to do very well and to this point (2016 model, 40K miles), I've had no mechanical issues.
Also, FWIW - BMW finally has a 3-row SUV on the market, the X7. It's Range Rover-sized, still not as large as a Tahoe. For the V8 model, you can't get near one for under $100,000, and quite a bit more once you add normal features. It has to be considered that I paid less than $60K for my Tahoe. I don't think it's half the vehicle a BMW X7 is at all. And again, I've had 3 BMWs.