The old meditation hall in Ramanashramam, where the Maharshi used to spend most of His time, is a prime attraction apart from the main temple and the Adi Annamalai temple.
The major road to the town, NH66 from Krishnagiri, is being relaid. Expect some bad stretches till the work is completed. Those travelling from Bangalore can consider the route Bargur - Tirupattur - Singarapettai - Chengam - Tiruvannamalai, thus avoiding part of the NH66. This route takes only 15km extra.
There are hotels suiting all budgets in the town, from 300 INR per day to over 5000 INR per day.
On a regular day it will take approximately an hour to worship at all the sannidhis in the temple. On special days like Pradosham or on festival days the number of people will be larger. On full moon days and Shivarathri day there will be thousands of people.
Ramanashramam is about 2km from the Raja gopuram, autos typically charge 40 INR. Adi Annamalai temple is a very old temple, almost exactly diagonally opposite to the main temple, on the other side of the holy hill. Much of the time there are not many people in the temple, and one can spend as much time as one pleases in front of the sannidhis. In contrast, in the main temple, one gets only a few seconds in front of the sannidhis.
Avoid Girivalam between 0830 to 1700, it can be very hot. Girivalam can be done any day. During full moon days thousands of people do Girivalam throughout the day, it can be crowded.
The Vedas chanting and devotees rendition of Akshara Mana Malai in Ramanashramam are a treat to listen. There are also quite a few temples in the surrounding towns like Tirukkoilur, Tiruvarangam, Nedungunam, Parvathamalai, Devikapuram, Injimedu. The two Perumal temples in Tirukkiolur and Tiruvarangam, both nearly 35 km from Tiruvannamalai, are ancient and as the priests in the temples say, one needs to have the "praptham" to visit the temples.
The weather can be hot during March to October. One can make plans about visiting Tiruvannamalai, but will be able to go there and see the temples and ashrams only when God Himself allows. Needless to say, there is such an amount of peace, and one has to tear oneself away from the place.