The obvious answer is to spend hours on the beach - but the area does have occasional undertow and sharks. Cocoa Beach pier is a tourist draw. Like a little shopping for beach wear and souvenirs - go to Ron Jon Surf Shop.
Check out nature tours on the Indian River - relaxing and interesting.
The industrial canal at Port Canaveral is where the cruise ships arrive and depart - can spend some time there. Cruise ships depart at 4 p.m. almost daily. Several good restaurants along the canal: Rusty's Seafood, Fishlips Waterfront Bar & Grill, Grills Seafood Deck & Tiki Bar. Have been to Grills several times - these places are right on the canal so you see whatever activity is happening. Grills folks will tell you, if you want deep fried battered fish, go to Long John Silvers. Kids want pizza - go to Papa Vito's on A1A. At the east end of the canal is Jetty Park and Pier. Need a walk - go out on the pier and watch ship traffic. Apparently, another cruise ship terminal is being built nearby. The canal has a submarine base - might see one coming or going while on the pier or on the beach.
Kennedy Space Center is northwest of Cocoa Beach a short distance - another good family tour. Check the launch schedule while you are there - could be something going up, but it's often in the middle of the night. Awesome sight and sound, even from a distance in the vicinity of the canal. Got a desire for Disney? Can run into Orlando area on the Beachline (tolls) and shop at Downtown Disney without going into any parks.
