Virgin reward availability doesn't always show at the 336 day mark. It used to a few years back, but now it is much more random.

If you are after PE to LAS you stand more chance than UC, but even then I don't think there are too many LAS rewards available. If I were in your shoes and two did happen to open up before the returns are available I would grab them, but it is always a gamble, often depending on how rigid your return dates are. Looking at a dummy booking for March next year, which has just opened up, there are several days with 2 x PE rewards - at least according to the website.

Alternatives to LAS are LAX and SFO then get a cheap internal to Sin City.

Booking one way rewards are not a problem with VS on VS metal.

Nick