Advise for first time visitors

Hi there,

I am considering traveling to Japan next year. First, we're a family of 3 (two adults and one 5 year old), and we would like to hit up Tokyo for about a week and spend two or three days at Tokyo Disney. The rest would be to visit the rest of the city.

Our second stop would be somewhere warmer. We were considering Okinawa. The flights are not bad in terms of price from Tokyo and accommodations seems affordable. It seems like it is cheaper to fly to Tokyo originally, fly to Okinawa, return to Tokyo and catch our return flight back to Canada. Seems like a ton of effort but it is cheaper than flying from Okinawa to Vancouver direct (please correct me if I'm wrong.)

Estimated breakdown in price (these are CDN numbers) :

Flight from Vancouver to Tokyo ~$3500

Accommodation: ~$1500

Disney Tickets: ~600

Return flight to Okinawa: $400

Accommodation: ~$1500

Do we need to rent a car in Okinawa? Is there somewhere else we could go for swimming that is cheaper or closer to one of the big islands?