There are 75 Vishnu Kshethra out of 108 Divyadesa, revered by Alvars. There are 108 Siva temples revered by Nayanars in the surroundings of Kumbakonam. No need to tell about more than 1000 Siva temples in Tamilnadu. There are six main abodes of Subrahmanya Swami in Tamilnadu with the name Arupadaiveedu. (Where Kumaraswami killed Tarakasura in one place, married Devasena in another place, got Brahmagnana in another place... like that), excluding Marda malai near Coimbatore, with a great temple of Subrahmanya Swami. No need to tell about Kanchi Kamakshi, Madhura Meenakshi like temples which belong to Parvati Mata. Many famous temples of Narasimha Swami are also there in TN.
Every temple and it's Kshethra have a history and legend of which, one can get through Google. We had visited more than 200 temples in Tamilnadu though I am pakka Hyderabadi and a pure Telugu person who doesn't know how to talk and read Tamil. We used only maps to get there and read the history before the trip. Now I tell some interesting facts and rare temples in TN for you, though we have many such temples in our Telugu states also.
Madhura Meenakshi is the sister of Lord Mahavishnu with the name Azhagar or Kalazhagar, Who comes to do marriage ceremony of Meenakshi with Sundareswar every year. Because at first, Mahavishnu did this marriage ceremony of Meenakshi, the daughter of Pandyaraja alongwith Parameswara who came as Sundareswarar to marry her. Azhagar comes here by procession every year from Azhagar Koil, which is also a Divyadesa with a great legend. It takes 2 days to understand the largest temple of Meenakshi and Sundareswarar. This temple has lotus pond, 1000 pillared Mandapam etc…
From Azhagar Koil, we can go uphill to Pazhamudhircholai (one of Subrahmanya Swami's Aruveedu Divyakshathras) and Nupura Gangai. These waters are used for the Brahmothsava of Meenakshi. While going to uphill from Azhagar Koil, turn head to see back the beautiful alaya Sikharam of Azhagar Koil. This Sikharam is called Somasundara Vimanam, brought by Indra. Tirupparakundram (one of Aruveedu) is also in Madurai, where Shanmukha Swami had celestial wedding with Devayani. Tirukkudal, the temple of Kudal Azhagar Perumal is also in Madurai, which is very unique in its style with three storeyed temple where Lord Vishnu lies in sitting, standing and sleeping postures.
Namakkal itself is very special place near Srirangam with Narasimha Swami and Anjaneya Swami temples. While returning from Himalayas to Lanka, a piece of Sanjivani fell from the mount, which had been lifted by Hanuman. Hanuman requested to see Narasimha Swami here. Meanwhile, Lakshmi Devi was doing Tapas to see Narasimha Swami in the same place. So Narasimha Swami appeared for both of them. One can observe very beautiful carvings of Narasimha Swami idols on the hill rock inside the temple. 18 feet Hanuman gives us goosebumps. A grand abhisheka is held to Hanuman for which 1000 eyes are not enough.
If you plan Rameshwaram don't forget to Visit Dharbhasayana (Tiruppulani), where Rama lied down for 3 days praying the Hindu Ocean to make the way to Lanka. The Ramasethu was built afterwards. One can see Rama here in three temples as Jagannatha (standing posture), Dharbhasayana (sleeping posture) and Pattabhisheka Murthi (sitting posture), side by side. One should not forget to bath in the sea at Dhanushkoti. I saw Guruvayurappan in Palani Murugan while watching early morning Abhishek here. Subrahmanya Swami looked like Guruvayoor Krishna.
Kanyakumari, Suchindram, Vaideeswaran Koil, Tirukkadiyur Abhirami temple (where the temple is bustling always with Shashtipurthi couples etc... One can get the lunch also here.), Srimushnam Adi Varaha Swami temple (the first foot of Varaha Swami on the Earth happened here), Siva temples in Kurthalam, Tirunalveli, Papanasam, Sankaran KOil etc.., are very famous temples with a great legend. Wherever you go you find a temple nearby your location. That's it.