It took me a minute to figure it out, but I think you are talking about Kona cafe at the Polynesian, right? If it is at the Polynesian then you can definitely stay around and watch the fireworks from the beach. I don't know how 'fun' the restaurant is, it's really just the main cafe for guests staying at the Poly, though they are famous for their tonga toast at breakfast! I don't think there is anything wrong with Kona (we didn't try it even during our week staying at the Poly), but I searched for general dinner availability on 8/6 and there are lots of places with better food and/or atmosphere.