It may depend on the cruiseline the age mix.
Depends on what you are looking for.
If you want port intensive, no formal nights, good food, no vegas style shows, no kids try Oceania.
If you want more entertainment and formal nights
I have heard HAL is good.
Alexandr Pushkin, Carnival-Holiday, HAL-(old)Westerdam, Orient lines-Marco Polo, Royal Olympic-Olympic, NCL-Dream, Dawn-Princess, ACCL-Grande Caribe, Oceania-Insignia (3), Regatta(4) Marina (1) St Lawrence Cruise Lines-Canadian Empress
Scenic River cruise June 11,2012