Early May was our jam for a long time. Once the kids were old enough where missing school that late meant missing exams, we started doing in September, then January, then a few times in October, then late May.
NOTHING beats early May. We'll be there again for the first time in early May (3rd - 14th - first couple of days at Uni) in 60 or so days. Can't wait. Weather is great - like others have said if it rains it rains for a few minutes then it's gone.
Crowds were always low\moderate. Don't know what it's going to be like now, but we're looking forward to it. That much I can tell you.
Enjoy!