9th: Stay back in Chandigarh, relax.
10th: Visit Chandigarh (Althought thereisn't much of tourist interest but then whatever you look forward to.
11th 4 AM take Kalka Mail to Kalka (you can also book a taxi which'd be better) for taking Shivalik Deluxe to Shimla. Enjoy the Toy train.
11th: Stay in Shimla.
12th:Stay...
more... in Shimla
13th: Early morning take a bus to Kullu (via Mandi). Take the earliest bus, plenty are available. 3-5hrs max it'll take.
13th: Stay in Kullu, go for river rafting. Have fun. Eat momos.
14th: Continue staying in Kullu. Get bored by it.
15th morning leave for Manali: (1-2 hrs journey): Enjoy the beauty of the route, its incredible!
16th: Stay in Manali. Eat. Drink. Have fun.
17th: Dedicate this day for the best segment of your vacation. Do a round trip to Rohtang Pass. Its a 2 hour journey one way. Up there you can go for skiing etc if you find snow. (In july you might just not, but its worth a try) Come back to Manali by evening.
18th: Take overnight volvo to Chandigarh, 5:00 PM departure bus will drop you there by 3AM, 6:30 by 4:30 AM and so on.
19th: Depart for Chennai.
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Its been merely a week since I did a trip to ALL these places. Every detail is fresh at the moment. You can shoot your queries in the comments. Will be happy to help.