My wife and I are both egalitarian and pragmatic about accepting split cabin assignments.

...Egalitarian meaning that we see each other as equally deserving of the opportunity to have a nicer seat. We accept no traditional gender roles such as "A man should always defer to the woman," or "The woman should always sacrifice her own satisfaction for her husband's." (Both are practiced in different cultural backgrounds we are personally familiar with.)

...Pragmatic meaning that we consider other factors beyond simply, "Whose turn is it?" While we're happy to alternate A-B-A-B if that's the only basis for a decision, generally we also consider factors such as: 1) I'm a big guy and a larger seat often means more to me comfort-wise than to my wife; 2) My wife has chronic pain issues and sometimes really needs the bigger seat more than I do; or 3) Either of us might have a tight schedule-- like having to work early the next day after a long flight-- in which case the upgrade means more to that person than the other.