I'm cruising around Hawaii next year with my Mom (69, can walk a long way on relatively even ground but doesn't do well with a lot of stairs, hiking, etc.). We'll have 1-2 days in each of the following places: Honolulu (flying from east coast, will be jet lagged here for sure!), Kahului, Hilo, Kona, and Nāwiliwili. Any can't miss destinations?