In the last two years I was involved with two older guys. The first guy I met shortly before my 24th birthday and he was 37 going on 38. I started dating the second guy around my 25th birthday and he will be 45 in February. From these two guys I have learned that I do prefer older men HOWEVER age doesn't mean as much as people make it out to mean.
When dating older guys, I think it's more important to consider things like maturity level, relationship status (is he divorced, never married, etc.), children (how many does he have, by how many different women, will he want more in the future, is there drama with the child(ren's) mother(s)?), his health. Those are the things that REALLY matter because the older the guy is, the more likely he is to come with some baggage. For me as a woman who is baggage free (no kids, no ex-hubby) and has her ish together (IMO, lol...own place, just bought a new car, good job, good credit) it is important to consider how much baggage I'm willing to take on. You have to be willing to accept ALL OF THAT BAGGAGE when you get into a relationship with an older man. And saying your cap is 5-10-15-20 years older really doesn't get to the root of the issues that might cause you problems with an older man.