I suggest you leave out the malls and the pubs. It will be the same throughout. being from Chennai, missing this is no big loss.
I suggest you visit:
1)Lal bagh
2)Cubbon Park, can go to MG road and UB city from here. Within a radius of 1km. UB city is hi-fi mall and most people do window shopping only there
. Also visit Vishweshariya museum, see Vidhana Soudha, High court, all adjacent to cubbon park.
MG road has lost its sheen thanks to Metro Construction. It will regain its former glory only after all the mess is cleared out. MG road/Brigade road and commercial street (2 km away) from MG road is a shopper's paradise.
National market is the grey market area where you get all electronic stuff.
3) Iskon Temple, though commercialized, its worth a visit.
4) Nandi Hills, worth a visit. Be there for sun rise/ sun set.
Itinerary I suggest-
I am suggesting this itinerary keeping in mind you are students. I know the kind of enjoyment boys seek, being one myself
.
Pubs are many across, don't worry about finding a good one. Also, if possible, try avoiding driving if possible. The traffic is chaotic and irritating.
Note: The itinerary I suggest is considering you have your own transport. If you are traveling by bus, so many places can't be covered
Start from Chennai early morning (around 4am). You will be in Bangy by 8 AM.
You can try Hotel Chalukya,slightly expensive, but at the heart of the city. Freshen up and start from your hotel by 10AM. See Vidhana Soudha/High court. Then go to the Museum. Head to MG road/Brigade/Residency road for lunch. Visit Garuda mall(very nearby) or shop in and around MG road/Brigade road. Head to Cubbon park,spend time till sun set, head to commercial street for time pass/window shopping.
Next day, start early morning to Nandi hills to catch sun rise (around 85km from the hotel). Not much to do around here, after break fast, head back to city. Visit Iskon temple, for lunch, go to Malleshwaram, hang out in Mantri Mall. Don't eat any thing in the mall. Head to the hotel called Halli Mane (10 min walk to the hotel from Mantri mall). Also try butter gulkand at the Bhagyasree gulkand store (1 min walk across the road from the hotel). Roam around the streets of Sampige road/8th cross Malleshwaram. The streets are unbelievably colourful on the festive day. Dinner and head back to Hotel.
2nd of September, visit Lal Bagh,spend time there. Lunch and travel back to Chennai