747 Have already bought tickets, so I can't end Hawaii stay with trip to Big Island. Am thinking, I may simply skip it this time and go some other time. (Or possibly gamble for something like standby -- Realize it would be a longshot during Christmas season, but I hate to have to buy tickets now when I haven't had time to experience Oahu.) There are plenty of things to do in Oahu, and the surf should be up on the North Shore. Thanks for the tip about the dolphins.
JA610 Thanks for the tip about rental cars. However, my brother, who says he rarely uses his car, has told me I can use his.