Your knees can tell you when your saddle settings are wrong. Too short and you get discomfort in the front of the knee, too long and you get discomfort in the back of the knee. My toes don't quite touch the ground when I am in the saddle, when I stop I put a foot on the curb, or slide forward off the saddle and stand over the top tube. Getting out of the saddle when stopped at a traffic light or such is a good time to let the blood circulate.