Completed the trip. Thanks to all who provided tips and suggestions. Below is how it went.
Day 1
Started from home at 4:14 AM and reached EC at 9:25.
Took the usual Tambaram, Manimangalam, Sripermbudur, Krishnagiri, Hosur route. 5 hrs 10 mts to cover 317 KMs from home which is 7 kms away from Tambaram. The time includes 45 minute break for BF and a 15 minute delay at Krishnagiri tollgate.
65 KM stretch from Sriperumbudur to Chennasamudram Toll is very bad.
Had breakfast at Saravana Bhavan on the right 8 KMS from Krishnagiri toll. Taste was good though a little costly.
From EC to Mysore (Ruch the Prince hotel) took the Kanakapura route. Though its 2 way, roads were excellent except for 7 or 8 KMs where relaying work was happening. Took 3 hrs to cover this 163 KMs. This is excluding the diversion that I took at Malavalli to visit Shivanasamudra falls.
Both the falls view point at Shivanasamudra were fantastic. I liked Gagnachukki Falls View Point a lot. I am thinking how the view will be if water is flowing at full level. Barachukki falls was also good, but the stairs were closed. So can't view the falls up close and we were disappointed. Will have to visit again.
Did notice Art of Living center on the way, but as we were already late, didn’t check in.
Day 2
Visited Dubare Elephant Camp in the morning, Namdroling Monastery at noon and Brindavan Garden in the evening.
Kids enjoyed Dubare Elephant Camp. When we went to Namdroling Monastery, some prayers were going on and we were not allowed inside the main hall. But seeing the mass prayer from outside itself was a different experience. Brindavan Garden was ok. We just roamed till the night lights were switched on and returned without seeing the fountain lighting as the crowd was unbearable.
Day 3
Visited Mysore Zoo in the morning and Palace (to see lighting) in evening.
Zoo was neat, clean, lot of green cover and the path was organized well. Though I don't like to see wildlife in cages, somehow the birds and animals kept here looked healthy and energetic to me which was good. But the space they were kept was very small, especially for Lions, Tigers etc.
Went to Hotel RRR at 3 PM, waited for 30 mts and seeing at the crowd it looked like it would take another 1 hr. So we left and went to Guru sweet mart, bought Mysore Pak and then returned to Ruchi to have a late lunch.
Palace lighting was quite an experience. Glad that I planned to see it on a Sunday and on time. Rwched there at 6:45 :-)
Day 4
Checked out hotel and visited Ranganthittu Bird Sanctuary. As this was off season - nothing much was there except regular Storks, Coromorants, Ibises, Darters and of course crocodiles. But the place was neat and clean.
Took 2.5 hrs to reach EC from Ranganthittu Bird Sanctuary via Mandya.
After having lunch at a relations house at EC, started at 4:15 and reached Tambaram at 9:20. This include a 15 minute delay at Krishnagiri toll, 30 minute delay at Chennasamudram toll and a stopover for diesel fill.
Only thing that we missed in our planned itinerary was masala dosa at Vinayaka Mylari / GTR and a visit to KSIC silk factory. Hope we will do that next time.