Thiruvannamalai is a reasonably big town. There are plenty of hotels to suit various budgets. If you want to stay in some Ashrams (like Ramanasramam, Yogi Ramsurath Kumar Ashram, Seshadri swamigal ashram etc) you have to make advance inquiries. Search and get details from the respective websites. Ramanasramam normally puts the condition that those who intend to stay there should be devotees of Ramana Maharshi.
Food is generally good in most Tamil Nadu towns, but they will be predominantly south Indian. If you look for north Indian food, do Google search and locate appropriate hotels to stay.
For going to Annamalayar Temple or for ‘girivalam’ (Giri Pradakshina), modest Indian dress code is desirable. For men the dress code is Shirt & full trouser, Dhoti or Pyjamas with upper cloth. For women the preferred dress code is saree or half-saree with blouse or chudidhar with pyjama and upper cloth.
Thiruvannamalai is normally a hot place. October, November, December are rainy seasons. I don’t think it rains heavily in Thiruvannamalai. December, January and February are nice, reasonably cool times. Not so cool needing sweaters! But if you intend to go on Girivalam early morning in these months, some extra protection may be needed. Once the sun comes out bright, it gets hot.
I noramally prefered starting the girivalam early morning by 4 AM , and ending by 10 AM. Girivalam should mean walking only. Taking a round in two-wheeler, auto, or taxi is of no use. If you are staying somewhere in the route of Girivalam, you can start from there and end there. (I normally stayed at Ramanasramam and started and ended my pradakshina at it, after visiting the Temple which is in the route). Many people begin the walking from Arunachala temple and end it there.
(picture courtesy: Temples In India Info )
There is yet another temple known as the Adi Annamalayar temple somewhere at half the travel route. It requires a little extra walk from the girivalam path to reach the temple and comeback to track. There are several small lingas to worship en route.
Almost half of the girivalam route actually constitutes a couple of busy main roads of Thiruvannamalai. The other side is more peaceful, scarcely crowded, with much less traffic. It is more scenic, greener, rural and serene. It is also a tarred road only.
You can carry drinking water with you and some fruits and snacks if you prefer. You will find lots of alms seekers en route and, if you prefer to donate some money to them and also to the small-temple priests, please carry loose cash in small denominations.
The ideal way to undertake girivalam is to go alone, chanting your mantra and filling your mind with devotion. Ramana Maharshi recommends slow walking. He says girivalam is walking-meditation. Of course the Arunachala hill is always there in your vicinity as you walk around, and the hill is verily the physical manifestation of Lord Shiva.
If you are going with a company, it is better to avoid unnecessary chitchatting and concentrate on chanting your mantra.
Many people say that doing girivalam on the full moon night is highly rewarding. But it will be an extremely crowded affair, with lots of noise and commercial distractions. I personally prefer to avoid it, since the girivalam is meant for personal spiritual experience, and not to be treated as a picnic or fair.
All the best to you for a peaceful and spiritually enriching pilgrimage.