We have two styles of Root Beer now on draft...
From Abita (New Rrleans), a very smooth creamy brew...
"Abita brews its root beer with spring water, herbs, vanilla and yucca (which creates foam). Unlike most soft drink manufacturers, Abita sweetens its root beer with the pure Louisiana cane sugar. The resulting taste is reminiscent of soft drinks made in the 1940's and 1950's before bottlers turned to corn sugar and fructose. Like earlier root beers, Abita is also caffeine-free."
From Victory (Philly), a root beer that is less coy and with more of bite.