The Spot is pretty cool, Bennos on Seawall is good but a little pricey for what you get. The San Luis Resort’s pool and bar is an awesome place to hang out.
Second vote on Sonny’s Place. Another that I wouldn’t quite characterize as a hole-in-the-wall is Huli Huli Hut on 19th, but have had good food/drinks there.
You might also like Jimmy’s On The Pier - on Seawall around 89th Street, I believe. Great views of the Gulf and decent food.