Each district in Karnataka gives you a very different experience. While Coorg is more to do with coffee estates and waterfalls, Shimoga is a blend of natural spots (bird sanctuaries/waterfalls etc) and historic/architectural places (lots of Hoysala temples). No wonder, there seems to be some co-relation between Shimoga and literature.
There is very little information about Shimoga on the Internet, and we had to contact friends to get more information about what to visit and in what sequence.
After discussing on various options, we finally decided to cover south Shimoga (places around Thirthahalli first). The basic plan was to arrive in Shimoga as early as possible, and then head towards Agumbe on day 1, covering as many places on the way, and then head towards Sagar the next day and see what we can cover in that route.