the stretch along the lake from port credit to Oakville is pretty nice, then you're stuck on lakeshore until burlington. Around the bay in hamilton is fun and there's some neat sightseeing points along the way. Grimsby is as far West as I've been so far.

Going east, my favourite stretch of the lake is from Newcastle to Port hope. If you take the GO train East to Oshawa, then oshawa to port hope and back is a reasonable Sunday ride.