MARTY!!! long time no hear - how's it going!!?
Best round to go to will be Cadwell - Party in the Park, August Bank Holiday - there's always good bands on that weekend. However camping gets booked up early - so I'd get booked in now!!
The other rounds usually have good after race partying too (on the Sat night)- however (personally) I wouldn't say that Donnington, Thruxton or Silverstone are particuarly spectator/entertainment friendly!
The last round at Brands is a good weekend too - usually bands & disco on the Fri & Sat night & then the end of season parties going on in various hospitality units! lol
xx