However, time share is a brand new concept in china. I personally would not buy any time share because there is no laws and regulations to protect costumers.
If you do have too much spare cash, I would buy a quality condo with a ocean view in 三亚. I am confident that that condo will appreciate in value. However, you will not be able to rent it out for cash flow as there is no demand for it. (local people buy and visitors stay in hotels).
Comparing the return of investment of owning a condo in 三亚 vs. 北京,I would put my money in 北京 as the return of investment is much higher in 北京。