Just checked with guest relations onboard the Infinity re: the question of sleeping five in a room. There are several cabins (not necessarily suites) which have two bunk beds which flip out from the wall. Add this to the single sleeper couch and the king bed, you can sleep five in a room. Hope none are sleep walkers!
With just one small bathroom to share among five, they must start dressing for dinner at 3 in the afternoon. Bathrooms, and a place to dress and undress in privacy, remain the big problem in sharing a cabin, even most of the suites... unless all the members of the party have an extremely close relationship.