How about a week-long celebration like Ramadan?
Ramadan is a month-long period of fasting (although the daily fasts last from dawn to dusk), which is broken by a huge feast at the end of the period.
We could certainly afford to celebrate metal for a month; four weeks dedicated to retracing the development of music and its various genres (with a little bit of classical music thrown in for good measure!), from proto-metal to NYDM and everything in between. A metal festival every weekend, bonfires, mischief, and good food (preferably something to complement the Hessian worldview--German cuisine anyone?) during the entire period.
I'm sympathetic to having such an event beginning at Samhain (or late October in general) through to the end of November. Throughout the States, the weather is beginning to cool, not yet bitterly cold--perfect for the aforementioned festivities. As winter approaches, we may wish to emphasize the nighttime mysticism of black metal!