In the St. Lucie /Stuart area, for fun and seafood I recommend Conchy Joe's, 3945 NE Indian River Dr in Jensen Beach. Lots of Old Florida flavor. If you can, get a table near the water in the evening when the bridge is lit up. Order the conch chowder & the mango plantains. The chowder recipe was published in either Bon Apetit or Gourment. Great raw bar, too.
For seafood, I also like New England Fish Market, 1419 NE Jensen Beach Blvd also in Jensen Beach, but it gets crowded, so insist on a booth or a table in a corner. They sometimes have a "bug in a box" lobster special. They also sell fresh seafood to cook at home.
For bagels, deli, and soups, go to Tradition Square in PSL, and eat at Bagel Brothers of New York, 10350 SW Village Center Drive,
Port St. Lucie.
Other places I like:
Pusateri's Chicago Pizza, 221 SE Ocean Blvd in Stuart, is my pizza choice. We head there whenever we can.
For a moderately priced dinner, we go to Delmonico Grill, 2801 SW Brighton St (I-95 Exit 118) in Port St. Lucie. Try the sweet potato fries and the Delmonico Steak Oscar. The restaurant is in the western part of St. Lucie County, near I-95 exit 118 and Tradition.
Look at the post below regarding restaurants in the Port St. Lucie (PSL) area and that will give you solid insight on establishments along the Treasure Coast (PSL, Stuart, Jensen Beach, Palm City, Ft. Pierce). That should help. There are some very good places to eat along the Treasure Coast.