If you are traveling from Bangalore or Eastern Coastal Road, the roads are superb. You might be traveling faster than what your Google navigation will say. But, if you are travelling from Kochi/Western Coastal Road, it is a single road. Roads are good, but with a heavy traffic through out the day. What other locations you can visit depends totally on which route you're gonna follow.
Roads connecting to Kanyakumari are pretty good to drive on.
don't miss the morning sunrise and also go to the Swami Vivekananda Memorial which is a boat ride away.
beautiful churches and temples to see on the way.
if your going through Kerala don't forget to stop at Kovalam beach and if through TN then please visit Rameshwaram
Kanyakumari is one the best tourist destination in South India. Don't miss visiting these awesome places in Kanyakumari.
1. Vivekananda Rock Memorial