Round Top Drive

If you want outstanding views of the city, make the drive around Mount Tantalus. Round Top Drive, as it is know, circles Mount Tantalus and was closed for a while due to rock slides. It is a short drive so don't make a day of it or anything. The main reason I would suggest going would be to fully grasp what Honolulu, Diamond Head, Punchbowl and Waikiki look like. Diamond Head is stunning from this view.

Directions:

If you're staying in Waikiki, take Ala Wai Boulevard, which borders the canal, until you get to McCully Street. Make a right on McCully until you reach Beretania Street where you will make a left. 

In a few blocks you'll come to Punahou Street where you will make a right. After .3 mile there is a traffic light at Nehoa Street. Make a left and go three blocks to Makiki Heights. Make a right. One block later you'll come to a small park where the road forks.

Take the right fork and you've begun your journey on Round Top Drive. The road is a long nine mile loop, so you can also take the left fork and return to the same spot.