We took a wagon tour of the valley in 2007 and it was a lot of fun. They take you down into the valley in a van and then you tour the valley in a mule drawn wagon. Our guide lived in the valley and she was very good. If you take an early tour and they have room, they are willing to drop you off a short walk from the huge black sand beach and let you take the next van back up. I highly recommend this tour. Here is a link to the web site --->
http://www.waipiovalleywagontours.com/
Do not even think about driving down into this valley on your own! It is a very steep one lane road with pull over passing spots that only people who know the road
well should try. When you are going up you can not stop because you will stall and you will have to back down to the bottom to restart your vehicle.
Before we meet for the tour, we went to the park at the start of the road and view was fabulous. It is a must even if you don't take a tour into the valley.
Enjoy Joe