See - there's

1. Madurai

2. Thanjavur and the surrounding temples (the navagraha temples, etc - besides the thanjavur "big temple" / periya kovil)

3. Tirunelveli - nellaiappar temple, followed by the "nava tirupati" on the road to tiruchendur, and tiruchendur itself .. [of course, if you say tiruchendur, all the "aaru padai veedu" 6 murugan temples)

etc etc .. depends on which god you want to pray to, and what your interest is - architecture? prayers? special puja etc rituals at specific places?