Sunday dinner? Not to $$$?
If you go to Sardinia or PB Steak or anywhere in Sunset Harbour check high tide times. The area will be flooded on Sunday during high tide. If you go at High Tide both of those restaurants will be waterfront, but probably not exactly what you're looking for. You can drive through the flooding, but probably not ideal.
That being said, PB Steak is a good option. Also, Petit Rouge is good and is only about a 10 minute drive West of where J&G is. It is not waterfront.