This prompted me to go look at my B&R upright, which opens on the left.

But I've found that which side it opens on is important not because of how it opens, but because that's also where the side handle is usually located, and I often like to carry my rollaboard with that handle when I'm in a crowd.

For that purpose, the left-side handle works well for me as a right-handed person. If I'm pulling the bag along with my right hand and decide to stop to pick it up, the handle is either on my side of the bag. Or, if I turn the wheels toward me when I stop, the handle is on the back side (as oriented to the way I'm facing). Either way, a much more natural place for me to grab that handle than the alternative.

With the opening, sometimes when I plop the bag on a luggage rack the zipper is facing me, sometimes not. Haven't figured out why each case happens, but usually when I'm opening my bag I'm in a place where quickly spinning it around is less of a hassle than the pick-up-and-carry situation.