I went by myself a few years ago and had a blast.  Granted, I went to COC more recently and am returning this year, I really had a good time at Windells by myself.  If i had a choice, I would rather go to Windells if I was by myself than COC, but would rather go to COC with friends (as in this year and the last time I went).  Its easy to meet people at Windells because you are pretty confined to the camp, whereas at Whistler you wander around town during the afternoons.