If you think of Karnataka- 1. Coorg (Madikeri) the weather will be cool 2. Chikmagalur for some offbeat trekking. 3. Hampi (If you are fine with hot temps) for some Historical UNESCO Heritage sites. If you think of Kerala - 1. Wayanad for its beautiful plantations. 2. Munnar - Hill station 3. Alleppey - Backwaters. If your fond of Temples and Hot weathers - Tamil Nadu - Madurai, Rameshwaram, Kanchipuram. Pondicherry - for Beach and to witness French side of it. 4. Offbeat in Andhra Pradesh - Gandikota - Grand Canyon of India. Taking necessary measures about the corona virus is on you. Few of the places mentioned above comes under the Radar. I hope this info works.
All four states of South India offer a lot of touristy places. However because of Corona outbreak I'll suggest you to stay safe and visit places that have no cases reported. Also avoid very touristy places. You can visit Pondicherry, the French capital of Tamil Nadu if you are looking for a laid back vacation. You can even plan a trip to Madurai which is rich in culture and heritage and will definitely satisfy all the goodies out there. You can also plan a two day trip to Karaikudi, where the chettiars used to live and catch a glimpse of the huge mansions they used to live in.