I voted in the 30s somewhere. But then I'm 33 and not married so maybe I'm prejudiced! I know for me personally that I am a completely different person now than I was at 18, 21, 25, even 30 so the person I may have been attracted to/thought about marrying at those ages, I wouldn't even look twice at now...but I think it is so individual. I'm a "slow grower" or that's how I like to classify myself! I learn so much every day, week, month, year....I dont' know if I will ever feel ready!
The "children question" can become a problem for the people who get married older though, like someone said...My mom had me at 27 and I can not imagine having my own 6 year old right now!! HOLY MOLY!!!

I personally plan to adopt handicapped and special needs children that many others wouldn't want or give a chance to so for me that isn't an issue but I do see how it is for people that want to have their own flesh and blood children.

To each, his own I guess.