I visited the hill station of Coorg in the state of Karnataka from Bangalore for a short two days. This was in the peak of summer, and Bangalore was already pleasant compared to scorching Chennai. Coorg was very cool, and almost cold at nights. It is surrounded by misty mountains, and has all modern amenities including super markets, plenty of restaurants, hotels, and home stays. We hired a car with driver to take us to Coorg from Bangalore.
We left Bangalore early in the morning on the first day, stayed a night at a home stay in Coorg, and came back to Bangalore the second day night. Given the short time, we made the most of our trip by visiting a coffee plantation, a hilly lookout, and the elephant camp. Coorg deserves a more relaxed couple of days to really take in the atmosphere, though I would recommend staying away from the downtown area, which is very crowded.