If you want to get to Koh Samui on the *A Airpass, you can take a TG flight to Surat Thani. From there, you can take a taxi (about 250baht or a bus for 90 baht, one hour) to the ferry pier where you get onto a ferry to Koh Samui (about 60 baht, 2 hours)...too much effor for me, but backpackers do it just fine.