Spend some time exploring the main tourist street in Naha, Kokusai-dori. There is enough going on there to keep all types of people entertained for at least a day or two. It has shopping, restaurants and cafes, nightlife, and more!
Just flying into Naha (the main airport) is not a tropical experience however. You must make your way to some of the smaller islands to truly experience paradise! I was advised by many Japanese people to visit Ishigaki Island. I found out that flights were quite expensive though, and that there are a group of small islands called The Kerama Islands just west of Naha where you can enjoy the same, if not better scenery! It is more convenient to get to these islands than the islands further south like Ishigaki because you can take a boat or ferry (which takes an hour or two depending on the which option you choose), and it's a quarter of the price of most flights this season!
The Kerama Islands are comprised of three main islands. Tokashiki, Zamami, and Aka. Tokashiki is the largest and most developed, followed by Zamami and last but not least, Aka. I visited Zamami Island, and more specifically Furuzamami Beach. It was only a 5-minute bus ride from the port and boy was it worth it! I was able to relax in an area which had incredibly clear water and stunning coral beaches! There were just enough people around to keep me entertained, but 2/3 of the beach seemed not to be of interest to humans. Thus, should you feel the urge to spend some quality time with you, yourself, and you, meander west on the beach and within 5 minutes of walking you will reach a relatively "people free" zone. Walk far enough west and the coral is smooth enough that you can lay down comfortably without risk of getting all sandy! The beach boasts some of the bluest water (on the ride to the island as well) that I have ever seen in Japan! The water in the Kerama Islands is among the clearest in the world, so it's no major surprise that snorkeling and diving are such popular activities in this region. Don't dare miss this magical place should you come to Japan on a trip! If you live in Japan, you have no excuses for not visiting either...except for fierce typhoons of course, so it's extremely important to research the weather in Okinawa before planning your trip!