My best use of miles is that which saves me the most cash that I would have spent on purchasing the goods/services in the traditional way (using cash and/or bank cards) even if I had no miles/points and which has the highest return per mile spent to save cash on such purchases.

I find the funny money valuation of miles using full-fare first class or business class award tickets to be amusing but unrealistic unless the purchase using miles/points is a substitute for a purchase of the same using cash or credit/debit bank cards.