Only problem is when you date older, and your parents date younger. I once dated a girl who was older than my step-mum (who's only 10 years older than I am). Was pretty awkward.
That older woman is a hard find: someone who is stunning looking (they have to be), commitment free, and likes younger men, but when you find one... damn. That's a good thing right there. My ex who I just spoke about was a redhead, perfect skin, great figure... damn it was good! Only problem was looking through her photos of her being smoking hot in night clubs the year I was born. That was an odd moment.
I normally date younger, but not significantly. I'm in my mid twenties, and my (different) ex girlfriend's little sister (who is stunning) was hitting on me the other day. She is 19. It was awkward, as I remember her when she was 11 years old.