So Mrs. Smyrnaflyer and I flew ATL/SFO with our dog. I elected this one time to use our expiring AMEX companion certificate. Of course, no upgrades. And because I was flying with an animal, no exit row selection either. So we were crammed into coach seats with the dog jammed under the seat, and the plane was full. Of course, the seat next to me was occupied by a rather large passenger who kept lifting the arm rest to give himself more room (I put it back down). Moral to story, if you fly with a dog, don't use the certificate!