You can also reach Lake Ontario from Georgian Bay through the Trent-Severn Waterway, but it's 240 miles and you'll have to take your mast down. Still, it's a recreational boaters paradise and you'd have a great trip.
For Lake Ontario, west of Wilson, Port Dalhousie is a good choice if you like restaurants & bars. 50-Point is in a Conservation Park so it's good if you like quiet and nature. Port Credit is a great place to stay during the Jazz Fest (www.portcredit.com
) and also has great bars and restaurants within steps of both marinas, but I'd stay at the Harbour rather than the Village Marina. Toronto Island has the best view and is my favorite, but you'll have to take the ferry to get downtown ($3/each) and off the Island. Marina Four is smack in the middle of downtown and a great deal, a few minutes walk from the Skydome and CN-Towner, etc. And finally, reserve now at Ontario Place for the Air Show, which I think is usually in September.