As far as the NW fare goes, there is not a whole lot of availability for weekend mileage running. You can get out this Saturday (the 10th) on the K-fare, but a same day turn is not available at least from DCA. Later in the month you should be able to do a same day turn for about 4,500 EQM ex-DCA (more or less from wherever you are) on a Tuesday or Wednesday. Unfortunately, the NW fare is only valid through Feb 28th, which makes running on it difficult to say the least.