I can tell you that, while I haven't tried to do a lot of them, I've had pretty good luck with saver awards on PenAir and Era within Alaska. That said, I'm not sure how PenAir/Era awards combine with AS awards from the lower 48 - i.e. if a domestic saver award will take you from lower 48 - ANC - PenAir/Era destination, or if you'd have to book an award to ANC and a partner award from ANC. My guess is, unfortunately, the latter.