The biggest mileage run bang for your buck both in terms of money, time, comfort and mileage maximizing, is the cherished international Business Class itin. While terrific ex-USA fare sales tend to pop up around Thanksgiving/Xmas/New Years to Europe, such fares are typically on offer close to year-round ex-SE Asia (BKK, MNL, KUL, PNH, HKG, CMB). Great 'bucket shops' can be found in BKK, HKG. So, suck it up and buy a (gasp!) Economy fare to SE Asia/Mideast, with a 364 day return date. Then, on day 363, rebook the ticket for another 363 days ahead for the change fee. And wah-lah, you have have a 2 year window to take advantage of plentiful fare Business Class fare sales ex-SE Asia/Mideast. Plus, great and affordable actual vacation destinations in proximity to boot while you are there. Most extreme example back in the day- NYC-CMB roundtrip in F was about $12,000, but CMB-NYC roundtrip in F was about $2700.