Erie Basin is a really wonderful little shop full of old, creepy and beautiful things, such as Victorian mourning jewelry (some with hair in it), Freemason masks from the 1900's, tiny children's rings from the 1700's, and all kinds of other treasures. It is really as much a museum as it is a store, and all of the items have a haunting and unique aura.
It's a sweet agave bar hidden in the fridge of a Mexican grocery store that use to be a laundromat. It doesn't get more Brooklyn than that but the tourists haven't found it yet so I highly recommend it. Music is really good and they have a great selection of mezcal. Felipe, the owner, also owns the adjoining restaurant Cerveceria.
The best place to see a dramatic sunset is right by Valentino Pier in my neighborhood of Red Hook, Brooklyn. This was right after a storm. It's wild and brilliant and peaceful all at once.