Hi,
I just come back from a trip in Okinawa, ishigaki, and miyakojima.
Miyakojima is for me the best place to stay. beach are totally amaging and gorgeous! its one of the most incredible travel than i made.
For okinawa, it was hard to get a nice place, so i stay in business hotel.
For Ishigaki, i use to stay to friend house.
For Miyakojima, i found
miyakojima paradise (check link)
and we rent one studio. Everything was perfect and staff so friendly.
For traveller who expect to travel on south island, i strongly recommand to visit small island. compare with Okinawa.....its totally more nice.