I spent some time in late Nov on this big, mountainous rainforest-covered island very close to the Malaysian Andaman border. It is 100% National Park and has no other accommodation.
Accommodation is in 2 areas - Ao Malaka at NP HQ and on Ao Molae abt 4km south. There are basic facilities at Ao Son another 4 km south where you can capmp. NP will transport you down from the HQ pier. All are fine beach areas.
Malaka has good value bungalows, longhouse rooms for 4 with outside bathrooms and tents for hire. I do a cover of other Malaka facilities including the amazingly good value restaurant in the Tarutao bungalow review section. Hey and wireless connection for laptops. Molae has brand new bungalows. Ao Son has camping only.
I checked the viewpoint on the cliffs behind Malaka, walked down to Ao Son and the track to the nearby Lu Du waterfalls which was badly signposted and underwhelming - and otherwise spent my time lazing on the beach, swimming and checking the great sunsets over distant Ko Adang. I didn't get to go to the Crocodile Cave or snorkel the best area at Ao Rusi where they made "Survivor Thailand" - both of which can be visited by hire longtail from Malaka. I gave visiting the lower east and southern coasts a miss.
Very nice, uncrowded, laid back place is Tarutao.