Although Shark Valley often offers good photo opportunities for wading birds and alligators, the best overall photo ops typically are in the Homestead section of ENP.
A particular favorite is the short Anhinga Trail at the Royal Palm Visitor Center, perhaps the most visited park location. It allows close access to wading birds, alligators and other freshwater wildlife.
Other good spots closer to Flamingo are the Flamingo Marina with its reliable population of salt water crocodiles and Eco Pond, a mile beyond the Flamingo Visitor Center.
Wildlife viewing/photography from a canoe is good at Snake Bight cove (near Flamingo) and Chokoloskee Bay (in The Ten Thousand Islands) before low tide when water birds feed in the shallows and on mud flats.
A good freshwater canoeing area is at Nine Mile Pond, 11 miles (18 km) north of Flamingo.