The flight ended up being fairly empty due to move-ups by about 5pm on Friday, so I didn't even bother to try. When I got to the airport, we had some time so I asked, and basically if the flight was full/oversold, they might have done it but if it were empty, change fees aplenty.

What I DID learn the hard way is that you apparently can no longer upgrade a companion at the gate without paying the GoFirst fee. 4 seats in F opened up, so I tried to put the 3 of us up there and my daughter kept flagging to charge as a paid upgrade. The GA called someone since it was early and no one else was bugging him, and apparently a memo went out regarding this change.

On the way back, I was able to upgrade us all to F at OLCI. Also, at PHL, a passenger was denied boarding and would have been my seatmate otherwise - a story for another thread.