On a family trip to Hawaii, we drove up to the top and walked around a little bit, then biked down all the way to the beach. Fun ride, but would have liked to explore the crater a bit, probably like walking on the moon.
A group of us got up at 3a and drove to the summit in the dark to witness the renowned "pink sunrise." It was freezing cold before the sun came up (and of course we weren't wearing anything appropriate for the temps), and when it finally did it was a disappointing gray sunrise I wouldn't have minded to miss. The best part though was a several hour hike down into the crater - very cool. Would love to go back and spend a whole day exploring around there.