personally, my island is all over the place. its mushroom-themed, yet we have a demon slayer theme park, gravestone and other haunted areas (yes, my island has its own lore), and a raymond museum featuring a blender and shirt raymond touched which i purchased for the modest sum of 1 million bells and a photograph of raymond along with it
I have a "Home Depot" area in my island (literally, I even made the Home Depot logo on a sign). I got sick of going back to my house or scrambling around the island to look for materials, so I keep spare materials, spare tools, and a DIY bench there. It doesn't fit any of the rest of the decor of my island, but I keep it because it's convenient. I put Able Sisters, Nook's Cranny, and my Home Depot all near the Resident Services to make a sort of shopping district so it would fit better.
Before I reset my island, I had a really nice sort of overgrown Italian village theme going on, with a lot of statues outside and ornate, European sort of decor. But in the bottom left hand corner was a Tiki bar lol. It didn't seem to fit with the rest, but I really liked those neon palm trees, sooo. Had to include it anyway.
I have a little random spa area on one of my beaches that just doesn’t go with any of my island. It was the first thing I “built” outside, and I want to get rid of it, but idk what to put there so it’s staying until I figure it out :>