Planning to go to Hawaii with the family with 2 kids age 5 and 8 this August. Staying in Oahu for 5 days and then flying to Kona for 4 days. Will be arriving on Kona at 4pm on first day and leaving at 8pm on the 4th day. Second day I figure to rent a car and head to Volcanoes. How long of a drive is it. What can I do on the 3rd and 4th days? Thanks.