Some of the suites ($$$$$$) can accomodate that many, however, your most economical alternative might be to book adjoining cabins. Good travel agents are made for situations like this.
Explorer of the Seas October 2013
Caribbean Princess July 2006, May 2010 & November 2012
Monarch of the Seas November 2008
Crown Princess November 2007
Celebrity Zenith November 2005
Enchantment of the Seas August 2004
We've found its cheaper to book 2 cabins, either side by side or across the hall. Also, the 2nd bathroom is invaluable when 5 people are all trying to get ready at once. We put the adults in one room and the kids in the other. I bring the old baby monitor with me to keep track of what's going on in the kids room.
Celebrity Century 1/09
Carnival Destiny 10/07
Carnival Destiny 9/06
Monarch of the Seas 3/06
Carnival Inspiration 8/05
Carnival Miracle 4/05
Carnival Inspiration 4/04
Sovereign of the Seas 4/03