Last year I went to my first major race at Mosport for the ALMS race. It was amazing, with a great friendly atmosphere both in the camping areas and the paddock. The teams were amazingly open and friendly, willing to chat. I think I made a post about it back before Kinja ate my old account. Exciting race too, somewhat sullied by a certain Porsche's leaky intake manifold.
All in all, I can't wait to see this year's race. I won't be going, but I should catch it online.