I hope this doesn't sound too judgemental, but I feel very strongly about this.
I guess I have a different opinion on what do with monetary gifts. I think if you are given a BLANKET gift of $20,000, you should first PAY OFF ALL DEBT! then put some in an IRA, emergency fund, regular savings, retirement 401ks, and then future children's college funds. If there is anything left, then you put money towards the wedding. If the $20000 is a WEDDING GIFT then you can use it for the wedding (but I would definitely pay off debt first). I think its important that we understand that a wedding doesn't have to cost 10% interest plus some at $40,000 for a one day event. Pay cash, pay cash, pay cash. If you can't pay cash, save up until you do. Do not go into a marriage with debt or wedding debt. I don't think its worth it and money problems are the #1 reason for divorce.
Sorry, I've been teaching all day and I'm on my soap box. XOXO.