Some of those I game with consider a 4x6 to be a "standard" size gaming table, and lots of modern rules are made to be played on a 4x6 (
FoW,
40K, Bolt Action, Black Powder, etc).
However, another group I game with prefers big historical battles using 1000+ figs per side. I am lucky enough to have a full finished basement to work with so I built 4 4ftx6ft tables. They can be arranged as a single table either 6x16, a single table 4x24 or as four separate 4x6 tables if we want to have multiple games.
If you go to my blog there's a post from last year that shows my table under construction.
http://www.goingaming.blogspot.com/2013/05/rising-from-ashes.html