Cranfield might be a good contender for largest number of different types visiting over a number of years in the UK - PFA Rally held there for a number of years which I think I'm right in saying often hosted 1000 plus separate aircraft over the weekend, plus the biennial Flight Business and Light Aviation show which also attracted lots of visitors as well as a range of exhibition aircraft. Good range of weird and wonderful types amidst myriad Pipers and Cessnas! Biggest aircraft there that I think I recall was a static Trident used by the Institute of Technology?