Yep, reading this thread I was wondering why no-one suggested Transaero. It's a good airline, new(ish) planes, and if you manage to get an exit-row seat, there is loads of room. This would be my choice.

I have done Sakhalin before - try to avoid the period immediately before winter and the thaw in the spring - lots and LOTS of surface water being sprayed over pedestrians by cars driving fast without any consideration for pedestrians.