Juor- My understanding from Rick Grassett a guide a CBs Outfitters on Siesta Key is that the prime action is mid June to mid July. He fishes right of the beach in his flats boat, but I know locals down there that beach fish and fish tarpon in yaks off the beach. Supposedly, all along "Shell Beach" and Turtle Beach on Siesta Key the fish are within fly range during tha period. They are definitely cruising the passes from the intercoastal into the gulf at that time as well.
I've not been there then, but I go to Siesta Key for April vaca every year and fish the beach each and every day for snook, jacks, trout, ladyfish, etc. Also lots of cobia around in June as well. Check out Rick's site for more info
He's a very helpful guy.
Plus, if you can't get tarpon, 25 lb jacks will tear up your stuff.