I would vote for the Pribolofs as well. The reason I haven't actually gone out there yet is for the reasons listed above. It can be expensive and a decent chance of getting stuck due to weather.

Another place I would love to go on Penair is Akutan, due to it being serviced by a Grumman Goose. I'm not sure if it's bookable using miles or the kind of voucher FTI has though. The flight is from Dutch Harbor, but it is possible to get to Dutch Harbor without getting on the flights owned by Alaska Airlines connecting through Cold Bay or somewhere. Not sure if that would be valid.