OK I got you covered!
For breakfast, go to Beverly's in SPBeach, at the intersection of Corey Ave and Gulf Blvd. You could also go across the street to Frog Pond - both are good, my fave is anything Benedict from Beverly's. After breakfast, go for a walk down Corey (heading away from the Gulf) and check out the cute shops and our historic theatre. Check out what's playing for later (they sell beer and wine at this old timey theatre!).
For lunch, grab a real Cuban sandwich at the Floridian on 107th on Treasure Island. Be sure to get some black beans and rice (with diced onion) to go with. This place has won awards for this sandwich. There's also good takeout subs etc at Original Pizza nearby.
For dinner, forget the all you can eat crab legs (they're from Alaska anyway!) and go for all-you-can-AFFORD stone crab claws (assuming you arrive after Oct 15, when the season begins). Best place on the beach is Middlegrounds Grill on Treasure Island. When I go there, though, I always order the fish special. They usually serve local fish like hog snapper Oscar, which is the best fish in the world, topped with a fried soft shell crab. Out of this world I tell ya! I suppose you could get a steak there too...but I can't stay away from their fish (and I sell fish for a living lol!).
Also, since you are on vacation, there are some great beach bars in the area. There's a cluster of three on the water at the intersection of 75th Ave and the Gulf. Twisted Tarpon is my favorite of the three (sit upstairs) and has good food. Also, you could make an evening of going to the beach bars behind the hotels on the SPBeach strip. Start with the BonAire hotel and head north from there.
Have a great trip!
10661 Gulf Blvd, Treasure Island, FL 33706