For local cuisine in St. Thomas, I like Glady's Cafe tucked in one of the shopping alleys. They also carry a variety of Hot Sauces, their brand, in house recipe. For more elegant casual dining, we enjoyed Blue Havana at the Marriott Frenchman's Reef. Beautiful restaurant, good service and well prepared food. Another place is XO Bistro in the Red Hook plaza area.
For St. John, believe it or not, being that there's a lot of mediocre island fare there trying to be "trendy"..the best place is to call in dinner 'to go' at Candie's Barbeque. She sells out too so make sure you call, then we just bring it over to our place (condo or hotel) after an exhausting, fun day of swimming/snorkeling. Then there's Aqua Bistro on the other side of the island. Big portions, quality food. Our favorite there is the parmesan encrusted grouper topped with lobster on a bed of risotto. That alone is worth the trip to the other side of the island. If it's not on the menu, you can request it and they'll gladly cook it for you.
Agree on Gladys' for STT.
We get take out from Candi's every trip. In my opinion, Uncle Joe's, the other BBQ place, is mediocre at best.
What type of food are you seeking? I am sort of burned out on the "nicer" restaurants as their menus are too mainland for me.
After 15 years of visiting, we stick to the established places where we can get local lobster and fresh catches. Every trip we visit the Lime Inn, Ocean Grill (for lunch) La Tapa, Miss Lucy's (Coral Bay) and the Shipwreck (for lunch)