Like I said, walking the Brooklyn Bridge is incredible, especially when the sun is setting. To make it even better head back along the Manhattan Bridge because the 2 both begin pretty close to each other in Brooklyn.
On your way stop at the corner of Washington and Water Street for that first picture perfect spot. Then follow the signs to the start of the bridge. It is VERY different to the Brooklyn Bridge but in a good way. It's much quieter people wise but you walk right next to the subway line so that's pretty noisy. There's a lot of street art too and a slightly different view of the city.
Worth making the effort if you have time.