-An airport that lines up with resident services
-Resident services far away from the airport
-A theme
-An island entrance
-A heavily terraformed island
You don't have to have a town theme! I have a mix of two themes on my island because I can't settle on just one. As long as you're building what you like, you don't have to follow a theme at all~
I also do not have a town theme! I'm just making it as I go along. If I like something I'm just working with it. If I ever want a theme I'll just have to re-do everything. I'm fine with that.
No need to have a theme if you don’t want one or if you’re having trouble thinking of a theme you’d like. Don’t feel pressured to have a theme just because other people do; it’s your town, have fun decorating it the way you want to decorate it.
Personally, since ACNL, I’ve been going with a medieval theme - specifically a Dragon Age theme but with some extras like a countryside that’s not based on any locations in any of the games, but it’s a bit more difficult to stick completely with or complete for the time being with the limited amount of options and choices I have for furniture that goes with the theme or has origins from medieval times (such as food items; I try as much as possible to use food, art and other items that were invented during the medieval age or close to). At the same time, I use some more modern items to represent something else. I’m very happy with my theme but from time to time I kinda wish I either had no theme or went with something different so I can work more with what furniture we do have instead of having some empty spots.
Absolutely not. I have a gnome village in one corner of my island, a beekeeping area, a zen inspired area, etc. If you want a theme for your island, do it. Otherwise just do what you like.
I go by whatever that looks nice and what fits the area. I don't strictly follow a single theme. That would make me feel restricted or something on what to do. I would just go by "Hey, I'd like to put build something here... This thing would go well here.." I I take inspirations from my previous towns on New Leaf. If anything, my island is more of like a natural town and I have areas and that they are connected to each other.