One suggestion - arrive to SIN or KUL with your miles, make it as your base (KL will be way cheaper to stay) and after that travel around using LLCs - AirAsia, Tiger, Jetstar, etc.
I would recommend to avoid Phuket unless going world's prostitution center is your idea of travel. You have huge selection for beaches and sightseeing - question is what your budget and what are your preferences.