River cruises are limited to two people to a cabin, generally. A few have a suite which can sleep 3, but not on every one. The largest lines are Uniworld, Viking, Peter Diehlman, Amadeus, Avalon Waterways. Uniworlkd, Viking and Avalon cater to North Americans. There is no casino, and only local entertainment. The ships dock right in the city where the sites are. Some, like Avalon, include excursions in the price. The guides are locals. The river cruises, of course, go where ships can't go, and are actually like long narrow motorized barges so they can fit under bridges along the rivers in Holland, Germany, Austria, Hungary, etc. The river cruise are popular with people who have already done the Caribbean, Alaska, Mexican Riviera, and Mediterranean on conventional cruise ships and are looking for something different. The passengers tend to be well travelled, and average age 55.