I agree with
@Beanz in that the main shops need to be in your main village (the NL version of the Able Sisters shop just looks kinda wrong as a result of being in Main Street, and having the museum in Main Street meant that you couldn't see the second floor exhibits in Dream Towns) and that the other shops (GracieGrace without Gracie herself running it, Katrina, Shrunk, Reece and Cyrus, the HHA, potentially Luna?) need to be in a separate area that's a plane or train ride away (having them be adjacent to the village itself takes away a lot of the feeling that you're in the middle of nowhere, imo)... but I also feel there also
needs to be travelling visitors who don't have permanent shops, just so it doesn't feel like the entire world of Animal Crossing is your town and this shopping area.
Leif, Kicks (mainly because one of the great mysteries of AC is "how on earth did Kicks go from being a lowly shoeshiner to a bloke who owns a shop?", and as a Cockney the man is
designed for having a little market stall), Saharah, Redd... have them be in your town one day, the shopping area another day and absolutely nowhere the other days. Have them be travelling the lands elsewhere, have villagers mention they do so in dialogue, and you've instantaneously expanded the scope of the world of AC.