I've done one and am about to do another from MSP. A positioning flight to PIT. Then the first time twice to SEA, and this up-coming time I'm going BOS twice (via DTW since that is how DL gets there from PIT). Not purist runs, as I've things I want to do at the destinations and some overnights are involved, but they work well for me.

PIT and the other three double BIS miles locations are of course your best bets. On the last one, a flight attendant announced there were 20 Gold Medallion members on board. I'm guessing a whole lot of them were doing just what I was doing.

Hope you find something quickly. The fares are a lot higher around Christmas, although they might run some last minute things.

Romelle