My flight back to SFO was a full one, so they offered free check-in bags at the gate to preserve room in the overhead compartments. I was pleased; I hate having to lug that thing around, worrying about space, and likely looking like a weak idiot while struggling to load it up there (although I do mourn the Elnette hairspray I left in my hotel room; fiscally responsible me weighed $12 hairspray v. $25 check-in baggage fee).
They seem to load the back of the plane first, a big plus in my eyes. People staring at you as you pass by to get to your seat gets quite awkward.