Yes it’s a lovely archipelago filled with landscapes making nightlife vibrant and popular. There are lot of nightclubs, to explore besides clubbing and boat parties.
From Manali Bharatpur is 17 hours away. You could opt for trains which go via kalka and reach Manali. Other way is by bus cost works out between 4K to 5k based on the bus you opt for.
Bangkok the capital city of Thailand is full of palaces, museums and markets to shop. You would neither miss night shopping markets nor great architecture. Pattaya is more of resort type of city, filled with clubs, malls and lot more of nightlife to enjoy. It is a lovely beach town. Phuket is more of Andaman sea which has great nightlife, mesmerising beaches and holds one of the largest Chinese festival every year. Pattaya is 2 hours away from Bangkok while Phuket is 12 hours away. My suggestion would be Bangkok, since you are anyways visiting Bangkok it would be better to cover Phuket and Pattaya as per your travel plans.
Bangkok being the capital has a lot of historic monuments and temples along with fast city life, nightlife, and shopping options.
Phuket is more laid back, has the big buddha, patong beach, an old part of the city as well as nightlife.
Pattaya is mostly for enjoying beaches and resorts. Very lively at night.
Krabi is the slowest and the prettiest of them all. Lots of water activities and island hopping can be done here. I would recommend 2N each in Bkk, Phuket, and Krabi
I have been to these places from Bangalore and would definitely recommend them! (distance is from Majestic Bus station)
Nandi Hills: 60km
Saavandurga: 57km
Bannerghatta: 36km
Wonderla: 37km Sakandagiri Hills: 60km
Big Banyan Vineyard: 29km
Big Banyan Tree: 28km Shivagange: 48km