Sunningdale and Swinley are unquestionably top class,and you would certainly not be disappointed with any of the above suggestions to make a third course. It all depends on what you are looking for. Walton Heath is a true championship set up, The Addington, Royal Ashdown and West Sussex are the most distinctive, while Woking has a special place in most GCA lovers' hearts because of its influence on early heathland architecture. I, personally, wouldn't bother with Wentworth, Worplesdon or Camberley Heath. If you find yourself opting, for whatever reason, for The Berkshire, St George's Hill, West Hill or New Zealand you will enjoy them immensely.
The time to come is obvious - the last week in September, so that you can travel up to the North-West (via Beau Desert, of course) and join in the fun of the BUDA Cup during the first week in October.