If you go such a long time, I would sugest that you do not only do Phuket!

There is so much to see in Thailand!

Visit Krabi, which has that "paradise feeling". Go a few days more south, and visit Koh Lanta, nice voyage with the boat! From there you can take a longtail to more remoted islands, like Koh Hai, or other Trang islands!

Koh Lanta is a bit less in beach, but "Long beach" has a nice tropical vibe, with restaurants and pubs, right on the beach! Much less people then Phuket! I would not suggest this, if you were only staying two weeks, but with two months, it will be a very nice change!

Although that Hua Hin has his own charms, it is not the best for a beach holiday! Lot of yelleyfish, sun dissapears early in the afternoon! Old center is nice though.