Westin Resort is good, but is a bit old. We were very disappointed last last time. Location of Westin is far away but this is what a Resort's lcoation should be.
Mandarin Oriental has big pool, children playground, at the back of the hotel, they have their own Resort. The swimming pool in the main building is under renovation in September, guests have to use their giant pool in the Resort area. No so sure if they have finished the work or not. Location of MO is near to all the major areas so last time we took this one. Worth to try!