I'm surprised Southwood Road / Muskoka Road 13 doesn't have it's own thread on here. I was there yesterday and saw a number of bikes. Colours are changing there; given the weird weather, it may be as good as it gets.
It's a nice twisty ride. There is one bend in particular that I always remember; blind corner, descending, decreasing radius, now with an added bonus of a huge pothole that you won't see unless you're going slow. There's also a few sections with wet leaves on the road and there were two SUV's running up the middle of the road. I heard there was construction and sand on the road earlier in the year, but I didn't see that.