Bangalore to Mysore, Mysore to Wayanad, Wayanad to Ooty, Ooty to Palakkad, Palakkad to Munnar, Munnar to Kochi, Kochi to Alleppey, Alleppey to Kovalam(Trivandrum), Kovalam to Ponmudi. Try this route. You can explore all the places.
Bangalore - Mysore -wayanad- leave the hills to beach ( kannur ) -thalassery (fill your tummy with kerala's most delicious food items.. especially chicken biryani from old Paris hotel)-kozhikode( where food , history ,love ,all come together ) - thrissur- munnar - ( visit top station where you are above the clouds)- cheruthoni( where you'll find what floods did to cheruthoni )- leave idukki district by thodupuzha - Kottayam- alapuzha ( relax in backwaters)-kollam - travandrum- RETURN-kollam-gavi( pathanamthitta district)-kottayam- thrissur-Valparaiso via athirapally falls ( 6-6 Forest check post) - valparai - polachi (46 thrilling hairpin) - palakad- nilambur( malapuram district) - gudaloor via nadukani - Mysore - Bangalore. You can go to Ooty from gudlur if you wish to.