Older Women and Younger Men?

In my last post, I talked about men dating younger women.  So how about women dating younger men?  I see a real positive in this - particularly considering that women have a longer life span.  How much age difference is practical or possible?  Five years?  Ten years?  A wider age range seems unlikely but I don't know.  What's happening with my fellow over-fifty females?  Have you dated a younger guy or dating one now?  I need input from blog readers - I only know so many women - I'd like to hear experiences of other women.