I have booked to LAS Sept 5th for 10 nights, do Virgin release more seats nearer the time as I want to sit upstairs but the website shows that the whole of the plane is booked.
Welcome to V-Flyer
Only 60% are available for seat selection (which is only a request) so the seat map does not show any availability. The rest are freed when on-line check-in opens 24 hours before the flight with the exception of exit rows and bulkheads which are only allocated at the airport.
In addition the first half of the upstairs seats have been allocated to Virgin Holidays. These may not all be taken by VH customers and you may well find these are freed up for you to choose