The theme for my island is fairy tales, and my favorite areas are ones I've made to match the theme.
This is supposed to be a Snow White and the Seven Dwarfs area, with some Soot Sprites (from Spirited Away) helping sort the mining products in the beach below. I took the idea of Soot Sprites on the beach from another island, but their carrying mining products was my idea. I wanted the giant mushrooms to highlight how small the Dwarves are. Then I got a Snow White cutout.
I also have a Jack and the Giant Beanstalk area. The "giant's house" is actually just one of my island homes, and I've got a bird coop that's supposed to look like one of the chickens is laying a golden egg, and a Virgo Harp standing in for the magical harp. My Jack is actually a dress up doll, and the beanstalk is a giant vine. I saw the idea with simple panel farm animal stalls on a dream island and have used the idea in three different farm areas on my island.
If you look down at the right angle you can see that I made a scaled down area on my secret beach where I like to pretend little Jack climbed up from:
My Mermaid Area:
In this one I had fun positioning rock items, basically. I was trying to combe the idea of a fairy circle being a portal to another world and the idea of old rock formations like Stonehenge together. I put little gyroids coming out to give the idea of a portal being used. I don't think any of that really comes across here, but it's still one of my favorite areas anyway.
I had to take this down when the snow melted, but this was also one of my favorite areas. I had a sled dog team and their owner settling down to camp for the night. He got his dogs food and water and is now warming himself by the fire. Before this I had a sled dog race setup, but that didn't turn out as well as I liked so I switched to this.
I've also got a Scarecrow display by my main farm. It's supposed to be a display of the moment when the Scare Crow R' Us 24/7 Security team is switching shifts and getting ready to clock out/in to watch the fields, with the pumpkin carriage to carry them to and from the site.