The 22 best islands in Thailand and what you can expect at each one:
Koh Kood,
Koh Mak,
Koh Chang (east),
Koh Samet,
Koh Lan Ko Tao + Koh Nang Yuan,
Koh Phangan,
Koh Samui + Ko Mat Sum,
Koh Chang (southwest),
Koh Phayam,
Koh Surin,
Koh Similan,
Ko Phuket,
Koh Yao Noi + Ko Yao Yai,
Koh Mai Thon,
Koh Phi Phi,
Koh Lanta + Ko Rok,
Koh Muk (Ko Mook),
Koh Kradan,
Koh Libong,
Koh Tarutao,
Koh Lipe
1) Crowded, Best Nightlife, Parties, Bars
2) Uncrowded, Peaceful, Quieter
3) Best spot for Snorkeling / Scuba
4) Hiking Trail, Waterfall Trail
Source: www.Thaitrav.com