Actually, Zilara is adults only. Ziva is much newer. However, there are many room types in varied buildings in Ziva; not sure what's available as an award. All Zilara rooms face the ocean. They aren't that far apart and you could walk, but there is the public bus or taxi option as well.
Ziva has some more protected coves. Zilara is along the strip of ocean and the waves and current can be strong/rough, depending on weather.
12.5k extra points for the 3rd person really doesn't get you anything. It'll be the same room.