My wife and I are planning a trip to Oahu tomorrow and will have a car to drive around on Sunday 5/17/2015. I'm planning on driving around the island to see the major sights.. And possibly trying to squeeze in a the diamond head hike and Pearl Harbor tour while I'm at it the same day? What do you think?

Pearl tour will take about three hours. You can get on a guided tour or do it yourself. If you go on a guided tour then there is no lineup to enter as the tour operators bypass the queues. Diamond Head hike will only take an hour if you are fit. Factor in parking and getting there. Driving around the island is about a three hour min trip with no stops. Hope this is some help. Good luck with your coordination.