I was on Kauai over Xmas, and used a 24-85 (near the wide end) 99% of the time. The other 1% was a 17-35. I only took my 50/1.4 and 70-200/2.8 out of the bag to leave in the condo so I wouldn't have to lug them around.
My most vital piece of equipment was a LensPen to clean the Hawaii sea spray off my lenses and grads. They are MUCH more effective than Pec-Pads or anything else I tried. Also, bring hard stop grads--two- and three-stop grads should do nicely.