Two – 2007, 2009. Both tough days out.
It is a great experience, but not an essential one. I considered giving next year’s a whirl, but mainly because I wanted to get back to the Pyrenees.
Last time I got a entry only place from an operator (at vast mark-up, and just arranged my holiday around it). Previous time was with a tour operator.
I did consider next year’s, but TBH (having done it – there’s the rub), I’d rather spend the same money and a few days col bashing, rather than avoiding fat Americans and the fear of the balai.
EDIT: favourite sportive has been my visits to Belgium for the Tour of Flanders. Now that’s a tough day out…. 😀