In my family parents wouldn't consider any girl under 23/34 for marriage cos they prefer the girls do be financially stable and have more maturity (I know this can be true of younger girls as well but usually someone in late teens is not going to be as mature and independent as a girl in her twenties).
Agree 100% with Noor Is A Bore.
Gypsy_lonely, the age of marriage tends to have more to do with the financial and/or social status/situation rather than how attractive the girl is. Girls who marry very young tend to be less educated (I used to know quite a few girls from Mosque who married at 16-18, none of them were particularly beautiful but they all tended to come from the same type of family setup, weren't planning on uni or working and rather than wait for a brilliant proposal to come along from someone really special they couldn't/didn't want to be picky and so got married off). Most of the girls I know who are really attractive have married in their mid to late-twenties cos they have waited to be able to stand on their own two feet and to find the perfect partner despite having received proposals from a very young age.
Also, marriage is a gamble but there's an Islamic saying:
'One day Prophet Muhammad (peace be upon him) noticed a Bedouin leaving his camel without tying it and he asked the Bedouin, "Why don't you tie down your camel?" The Bedouin answered, "I put my trust in Allah." The Prophet then said, "Tie your camel first, then put your trust in Allah" (At-Tirmidhi).'
ie. us Muslims should not just stumble into marriage (or any situation) blindly with the excuse that it is a gamble and what happens will happen, we should use our common sense to ensure compatibility, attraction etc and not just put things down to fate. Things like agreeing to marry someone u've never met would come under this imo.