Fallout 3 locations project
The common room is provided for the use of Rivet City denizens that cannot (or will not) rent a proper cabin on the upper deck. The former sailor quarters still have functioning naval cots, providing a rudimentary sleeping environment, with a number of desks, a sofa, and a table provided for the convenience of those sleeping inside.
The list of Rivet City denizens sleeping in the common room includes Ted Strayer, Mister Lopez, Mei Wong, Tammy Hargrave and her son, James. Cherry will move in, if liberated from Dukov. Of course, the Lone Wanderer can sleep here as well.
The Rivet City common room appears only in Fallout 3.