If you want to see some nice sunsets, you'll have to make the trip to Polihale Beach Park. As I've said before, there is no road that goes all the way around the island. If you go north you'll turn around at Ke'e beach and if you south from the Pono Kai you'll end up at Polihale.
The last 5 miles are on a pretty rough stretch of road. Some pretty big potholes and it would be really muddy after a rain. We had a Jeep on our last trip so we went all the way to the beach. I did see some cars there and as long as it's dry you should be fine if you take your time but a Jeep will make you feel more comfortable. You may want to check with your car rental company, there may be a restriction about going here so if you would run into a problem, you could be on your own. I never did check to see if the was any cell service there.
It is a beautiful beach and you can see the island of Ni'ihau. Ni'ihau is the home of the famed lei makers of the Ni'ihau shell leis. There are some tables and toilets at the beach so you can enjoy a lunch or dinner at sunset.