Tammy,

I have been on every boat tour for the Lighthouse Walk. Last year I was on the Baily's Harbor boat but we never got to Cana Island. Boat problems! The best boat ride and the longest is: The Island Clipper, you see the most lights than any other ride.
You won't see all the lights over the weekend so I would only do one boat ride.
In my opinion I would do Cana Island first thing on Saturday morning or Sunday morning. You have to take a shuttle bus and then walk to the light.
You will have a great time.