I have been to Maui twice, Oahu twice and Lanai once. Thinking of going to Kauai but worried there isn't enough to do for activities. The Big Island seems to have a lack of sandy beaches. Molokai is much rainier (from what I could observe from Maui) and too quiet. Where on Kauai and Big Island are the areas that are most affordable / have the best weather? MUST be able to snorkel in safe waters. Hiking is not an option due to mobility issues with my traveling companion. We want beach, water, sunshine. Suggestions?