I've never used chains. The really good ones are waaay too heavy to lug around. If I used one, I'd probably go for something short, such as the Kryptonite NY Noose, and use the "around the rear wheel and steel pole" method, the same as with a u-lock.

Some messengers here in Houston like the longer chains because they don't have time to hunt for a steel pole that fits a u-lock. A bigger chain will fit around the rear wheel and a telephone pole, or street light, or most any pole you can find. They are willing to struggle with ten pounds of chain in trade for the convenience of parking at any building in town.