Fort Desotto Beach - St. Petersburg, FL is a great beach to see other thongers!
Excellent Beach to always find other thongers at this beach - pretty much guaranteed.
In my opinion this is one of the best place to thong in all of the Florida beaches.
Be sure to park close to the actual "Fort" itself and then head to the northern most area from the fort. Many who know where the thong area is will be parking along the road and walk through the grassy / wetland areas.
If this URL from this map works - the location of the thong area part of the beach is where it says "Gulf of Mexico" and where there is a handicap symbol and a bike caption shown. http://www.pinellascounty.org/park/maps/color/amenities/FortDeSoto.pdf
http://www.visitstpeteclearwater.com/article/fort-de-soto-park
Enjoy one of the best thong beaches in Florida!