Wedding blessing for two grooms? and toasts?

My brother and his long time partner are getting married this weekend, hooray!

All of the family has been asked to bring a blessing to their wedding ceremony. Most of the traditional ones talk about "starting their new life together" and things like that.

What I'd like to do is honor their already long (going on 20 years) loving relationship, between thick and thin, surviving the disapproval of a still-too-large segment of society, and to send our best wishes for the rest of their lives.

Any suggestions would be welcome!

And while you're at it, know any good toasts? I'll have to do some of those, too, and I think I've only done that once or twice in my life.