David T. Kennedy is a charming waterfront park with walking/cycling trails, a dog park, outdoor fitness equipment, volleyball courts and the Instagrammable “Miami”-etched benches that face Biscayne Bay. After a scenic workout or some leisurely dog- and people-watching, cool down with a frozen lemonade from the A.C.’s Icees truck, which has had a permanent spot in the parking lot for more than four decades.