There is one main settlement on the island of Ilha Grande, Vila do Abraão. It has a lot of restaurants (some on the beach), stores, a laundromat, and small clinic. As I mentioned in another post, there are no banks so it’s important to take enough cash, but credit cards are generally accepted.
There are two main roads through town. One runs along the beach and has the pier for boats leaving for Angra dos Reis and some tours.
The other road loops around the back of the village and connects to other smaller roads.
There aren’t any points of interest in Vila do Abraão other than a small church, Igreja de São Sebastião. It’s mostly a place to eat, sleep, book boat tours, or get things done.