I booked 2 F award tickets last month. As many say, use VA as the same flight via united is around 220k instead of 120k miles.

The key I found with availability was checking the united site versus the ANA site/expertflyer as partner availability seems to be different than ANA/actual availability. Once I had two seats bookable through United, I called VA and their agent was super helpful. When we finished she seemed impressed that I actually knew availability and said that a lot of people had been calling for ANA flights recently and demanding to book flights that didn't have partner availability. Thought this might be worth passing along.