Easy way to drain water heater?

After experimenting for a few years, I prefer to leave the water heater full of water unless I'm expecting the weather to freeze. Leaving the tank empty doesn't dry out the interior even if you leave the vents open, it leaves a nice moist environment with a lot of surface area for scuzz to grow on the walls of the tank, and leaving it with the vent and drain plugs open lets dust, spiders, and pollens into the tank. Leaving it full of city water leaves a lot less surface area and available air for crud to grow on, and since it is pretty much sterilized when you used it last from being heated to a pretty high temperature, not much will grow in there. A simple flush before use after storing it full of water for more that 3 or 4 weeks works really well for me.