Continental.com is pretty good at showing *A award availability.

1 Sep is probably going to be tough so close-in, plus it doesn't help being close to Labor Day weekend in the US.

Looking at CO.com with some random dates, I'm seeing some limited availability at what it considers Business on 3-class planes, or First on 2-cabin (what that equates to on Virgin I don't know offhand) at the SaverPass level of 50K each-way:

- The 4th shows a couple of options with UA LAX-JFK and connecting to Virgin for JFK-LAX.
- NZ 002 LAX to LHR available on the 6th.
- Virgin flight returning on the 16th with availability.
- CO's calendar shows a smattering of other dates with possible availability in Sep.

You're probably going to have to be more flexible on the dates for it to work at this point. There's a bit more availability in Y if a specific date is more important than being in a premium cabin. You can or mix and match cabins on the out/in-bounds with the 1-way awards on CO.