Listen, you are always looking, the interest never ceases.
I have a daughter and even if I were single (I am good and married) I could not take an interest in any woman younger than my eldest child. Just doesn’t feel right. I am 35 years older than my daughter and that should give you an idea of where I would draw the line.
But in most cases, you are going to be more comfortable with someone approaching or even past your own age.
The other comment I would make is that if you were comfortable approaching women when you were in your twenties or thirties you will retain that skill even if you are in your sixties. The reverse is true also, in my opinion. If you were uncomfortable approaching women when you were younger, you are not going to be better at it later in life.
SRM