After two visits to Maui, this winter was my first trip to any of the other islands. We started on Oahu, which felt like a cross between Hawaii and mainland. It has a real city, and highways, and streets with mainland-style English names (not a majority of streets, but a lot). Lots and lots of people, and traffic jams. Because the tallest mountains on Oahu are around 4000 feet, it doesn't have the weather/desert dichotomy of Maui, with its nearly 10,000 foot volcano.
Possibly the thing I noticed most, after getting used to the idea of a real city in Hawaii, was that we didn't see a rainbow the entire first day. When we didn't see one the entire second day, I noticed it even more. We'd gone all around the island, and up in a helicopter, been to a beach and a waterfall and various elevations. Where were the rainbows? Yet another way Oahu is more like the mainland, I thought.
But then we spent 6 days on the Big Island - on the water and up the mountains, in the rain forests and the deserts, on boats and helicopter, all over - and still no rainbows. As we were flying to Oahu for our last day, I was thinking about this. About how I'd spent a total of 10 days on Maui in two separate trips, and I don't think there was a single one of those ten days when I didn't see at least one rainbow. Some days I saw 3 or 4 at separate times in different places.
... then we flew over Maui, which is between the Big Island and Oahu, and we saw a rainbow down below.