There are only a few weeks left in 2009, and frequent travelers across the country are staring more intently at their mileage statements than Santa does at the naughty/nice list. The stakes are high: miss the elite cutoff, and a year of upgrades, accelerated check-in and other perks disappear. For passengers who see gold or platinum status levels within reach, year-end "mileage runs" can make a great investment.