I just returned from a HP TUS-SEA trip for my wife's family reunion.

My stratagy was to upgrade Cathy using mileage, and then take my chances getting a CO Platinum upgrade for myself, rather then taking chances that space would be available at the airport. When I called 2 days in advance for the outbound upgrade I was told that F/C was available on only one of the two segments. At the airport I was upgraded at check-in, and the agent gave back the 10k Onepass upgrade certificate with the boarding passes!

On the return it was the same, I was told that F/C was full on the SEA-PHX flight when I called 2 days in advance, but was upgraded when we checked in about 1-1/2 hours before the flight. Again the agent did not take the OnePass certificate, the boarding passes were marked CO Plat. and Plat Comp.
In the end all was well, we got to sit together and go F/C, and I still have the upgrade certs. for our next trip.

In the past I had a good success rate and was happy with the companion upgrade policy as a OnePass elite on both CO and HP. The new system makes it more complicated and difficult for a couple who would prefer to sit together as well have a reasonable chance to upgrade. I have been told by Continental that they would allow keeping coach seat assignments until check-in at the airport if one of a couple is able to obtain an advance upgrade, however with HP the seat assignment is lost at that time.