We did my parents 45th wedding anniversary a few years ago (my mother is quite ill and we aren't sure if she will make it to the 50th). We had my parents re-new their wedding vows and there was a mass to go with it (they are Catholic). After that we had a little afternoon tea for their friends and then a dinner with the immediate family (brothers and sisters).

Everyone seemed to enjoy it and we heard good things back from the relatives.