The unisex bathrooms may have urinals. Though we can legislate that bathrooms be open to all, we can't legislate the nature of the female anatomy (actually, you can try, but only terrible senators from South Dakota attempt it). If you don't need the stall for anything but tweeting on the john, save that open seat for the next lady who's been waiting patiently in line.
5. Don't Hog the Stalls