Well it is just tourist attractions or temple visit or beach visit ... depends on that you may customize it .
Find an tour operator and dicuss with your focus(theme).
Here some different combinations..
http://www.incredible-south-india.com/south-india-tours/index.html
All govt tourism sites listed below in the link.
http://www.incredibleindia.org/layout/state_tourism.html
Highlighting Major Places just for an idea. Some place you may skip,
Andra
Hydrabad : Husain sagar , Palace , museum , charminar ( 1-2 days)
Vishag : beaches (1 day)
Tamil Nadu/pondichery
Chennai : Chennai Mahabalipuram, Kanjeepuram (2 days)
Pondicherry (Auroville, POndicherry) 1 day
Tanjavur : ( Temples around Tanjore, palace, prakatheeswarar temple,) (2 days)
Rameshwaram (1 day)
Madurai ( 1 day)
Kodaikanal (hillstation) 1-2 day
Trichendur , thirunelveli, courralam (2Days)
Ooty, mudumalai ,Coonor ( 2 days)
Kanyakumari ( kanyakumari ,suchindram padmanabapuram) 2 days
Kerala
Thiruvananthapuram (kovalam, thiruvanantha puram, varkala) 2 days
Kumarokam ( 1 Day)
Munnar, Hill station, Tea estatesm, thekkady ( 2 day)
Cochi - 1 day
Athirapalli vazhachal falls
Vydri vayanadu 1 day
Karnataka
Bangalore 1 day
Mysore 2 day
Coorg 1 day
Jogfalls 1 days
Hambi 1 day
Goa : 2 -3 days