Horse boarding in the Mardi Gras state of Louisiana will provide you with 140+ horse friendly park trails. The state does have mild winters yet very hot and humid summers with 62" of annual rainfall. Sea level salt marsh stretches coastline, and inland for up to 25 miles in some spots.
From there the land gently rises into a wide coastal plain (or prairies) with a few rolling hills to the east and west. The state has critters from black bears, snakes to alligators. You can expect a full range of boarding options- pasture, stall and run in shelters.