Originally Posted by Gardyloo

This is quite apropos for the OP. For example, right now (through the next few days) AS is having a 30% bonus offer on purchased miles. For $550 (say GBP365) one can buy 26,000 miles from AS, good for a routing of, e.g., SEA/SFO/LAX//MIA/EWR/ORD... - ANC-DUT-xANC-SEA/MIA/EWR... etc. (in Y, which of course is all that's offered out the chain.) AS permits a stopover in SEA or ANC (or both? Don't remember) on any award redeemed to Alaska from any point in the lower 48. This is one of the rare occasions where buying miles is cost-effective.

AS' mileage plan is used widely as a "second" FFP for many people who principally use AA, BA or DL FFPs, since AS allows earn/burn on a wide variety of partners including the aforementioned AA, BA and DL, but also AF, KL, QF, LA, FJ and others.