Friday the 13th can be an excellent event. It has a scenic location: lakeside, lots of farmland/orchards, the roads are decent if not that twisty, several thousand other bikers and a lot of really interesting/unusual custom jobs. You've got your various bike clubs being represented, lots of vendors, beer tents, live music, decent food in the town restaurants and pubs.
The first couple of times I attended Dover were pretty boring....mostly walking around in 100 degree weather looking for other VMax's. Last year I went to Dover and did my own thing: took in some of the live music acts, visited a beer tent or two, watched some eye candy at the beach, visited the vendors, and saw a lot of nice bikes.
The Bike Rally in Parry Sound isn't that great IMHO.
Blaine