We have an STK in NYC. As a weird rule of thumb, while on vacation, we try and stay away from places and things you can get anyplace else. I know we kinda break that when we stuff our faces at Sprinkles, but for restaurants we try and stick to places unique to Disney. Worth noting that STK is loud and very much feels like a hybrid club/restaurant.
Never been to Boathouse but it's on the list.
Brown Derby is good. It's often forgotten about. We had friends down in Disney during Easter. They had lunch here and really enjoyed it.
We love Narcoossee's, enjoyed Artist Point, and are big fans of Yachtsman. Honestly? My thinking is this: you have free dining. Let's throw away the idea of "wasting TS credits". To me, I'd spring for a place I wouldn't normally go to. I'd do Cali Grill just because I wouldn't pay OOP to go there, it's a Disney classic, and if times right, you can get an awesome view for the fireworks.