After lots research on the islands of Thailand, I settled on Koh Lanta. I wasn’t wanting parties or lots of crowds so that eliminated a lot of the popular islands.
To get to Koh Lanta, the easiest way was to go through Krabi. After experiences using South American transportation in the back of my mind, I opted to fly into Krabi, spend the night then go onward to Koh Lanta and repeat this on the way back. To my surprise the timing is great and you could probably omit the night(s) in Krabi.