If you have some time in Naha, and want to do something free, I highly recommend visiting the Fukushen Gardens which is not too far from Kokusai Dori (International Street), in the downtown area.
Okinawa, being so close to China rather than mainland Japan, has a very strong Chinese influence that you would not see in a place like, say, Tokyo. And Fukushen is a beautiful Chinese style garden, built in collaboration with Naha’s sister city, Fuzhou. It has lovely paths that wind through pavilions, ponds, and waterfalls, and is a nice escape from the hustle and bustle of the 58 highway, running through the city.
Much to my surprise, The Kid really enjoyed this place, and liked walking over the stone bridges and climbing the steps up into the hills. Oh and hiding in the pagodas!
Be sure to wear good shoes if you want to walk behind the waterfall!