In reading this trail....get a group travel specialist.
We used Erica (her website is below) for my parents 50th anniversary cruise. We had 50 family members/guests. She handled all arrangements and gave us free cabins that the cruise line (Royal Caribbean) gave her for every 8 cabins booked. She also arranged an on board party.
http://www.vacation.com/travel-agent...a-papley/41929