Looking at what you have all ben inputting.. I reckon a game of chance will be best :)
I want to make it fair to all...
Also as steve says, a lot of us rooks would probably give the prize to a pawn anyway..

I want to make it as fair as possible, Also your idea IMupChucKing is good too... I could run 2.. one for the higher ranked.. one for the lower...

I was going to do a years membership.. but I could split it into 2 six months..

anymore suggestions/help appreciated