Hi,
I have lived in Phuket for 6 months, and love it, I never want to leave!! Anyway, beaches...depends what you like. Tourists a plenty at Patong and Karon/Kata. Personally I love Laem Singh, but can also be a bit busy. However has bonus of a great restaurant! Nai Yang is stunningly peaceful and very lovely, while Nai Thon Noi and the one further south with a funny name (hin gluey??) are easily the most beautiful if a little difficult to get to / find. Do not swim at Surin, there are nasty rip currents, and I think Bang Tao is boringly straight and big. If you like it quiet, explore the north and north east part of the island, where there are few tourists and much beauty to be found. Rain Forest on one side and beaches on the other...what more could you want! At the south Rawai and Nai Harn are OK, and Phrom Thep Cape is worth seeing at Sunset if you can find a spot amongst the other tourists. Enjoy!!! Its a stunning place, and well worth getting to know.