The largest wedding I have ever done was a favor to my cousin. The wedding party had about 11 girls and about 8 guys. I am using the term "about" because I would like to forget that day and all of the details. Everything was a nightmare. She wanted photos that looked were really creative however the bridal party was very snobby and impatient. The best man did not want to take his toothpick out of his mouth, there were several occasions when I wanted to call him everything except a child of God. Then she wanted this mega family shot with about 75 people.
On the serious side I felt that it was just to difficult to work with such a large group of people, the attitudes, the time restraints. I no longer accept large weddings. Many people will say that you will lose a lot of customers but I have not. Just the ones with huge bridal parties and I am fine with that.
*By the way make sure you have a wide angle lense for group shots.