If you are really worried about your knees, get
Dermablend. It works wonders and the setting powder makes it stay. Under no circumstances wear open toed shoes with hose. But if your legs overall worry you, as VS said, wear GOOD sheer nude hose (good = best and sheerest you can afford at Macy's, Nordstrom etc).
I am ready for the whole no hose ever thing to be over as a lot of women do it who really shouldn't.