I had been to TV Malai last weekend (5,6 Nov, 2010).
We had struck this place out (per Tbhipian's suggestion, to avoid diwali rush) and zeroed in on Yelagiri, but at the last min things took a diff turn and we ended up in TV Malai.
The route that we had taken was
Blr -> Hosur -> Krishnagiri -> Chengam -> TV Malai. And as told by numerous other all thro this thread, the roads are real bad, your avg speed dips. Esp so if you are travelling in a car. On our way back we had seen how a skoda’s bumper disintegrates, the chap had thought the water on the road was a small puddle, but it turned out to be crater. I think he damaged all the bumper mounting points in that crash.The pot holes are huge, so you have to slow down and step in and out gracefully.
The entire stretch from Krishnagiri to TV Malai is lined with trees. The place around is real green.
TV Malai has foreigners and beggers in abundance. I was surprised to see the same Rs 8 coffee being sold to a foreigner for Rs 15. And everyone seems to accept this differential pricing in the same store.
Traveller Tip: Diwali is a MAJOR MAJOR festival in Tamil Nadu. Almost every single hotel closes down on this day. We had a tough time finding a place to fill our tummy. May be that’s why, our late lunch + early dinner at ‘Arunai Anantha’ was superb.
Speaking about Arunai Anantha, the resort is good, very clean, nice and green, courteous staff, open parking, they even have a swimming pool. That’s the good part, the other side is, its kitchen is one of the badly ‘managed’ one. From the time they take an order to when they deliver the food, Man! The clock just ticks on and on and on. Not a recommended place if you are in a hurry. Surprisingly the food is tasty, may be only one cook is managing the whole kitchen. We did not stay here, had dropped in only for our meal.
WARNING: Visit this place, only if you have all the time in the world, and you are not ‘that’ hungry, you can place the order, sit around, chat, and by then when your tummy starts grumbling, they are there to serve a tasty treat. (Ps: We had tried only dosas, idlys, vadas & chilly gobi. And I can vouch for that

)
One suggested stopover on your way back to Bangalore is the
Sathanur Dam. Pretty huge place for a dam, nice picnic spot. We were there when the cyclone Jal was paving into TN, so there was a nice drizzle, maybe that is why, it looked nice and green, and not overflowing with people like in the temple.
The hill behind the Ramana maharshi ashram is worth every minute spent climbing it, the cave, the water fall, and the monkeys; it is all worth the trouble. We were lucky, it was cloudy on our way up and we enjoyed it. There is quite a bit to climb, it might not be easy on the knees for the elderly. The path is laid with stones, not as easy as walking on a paved path.
Thiruvannamalai - recommended place for a 2 day trip. Choose a cloudy day. Not the rainy ones, as the roads aren’t great, rains and bad roads, just don’t add up nice.