The Dusit Rayavadee Premier Resort's is pobably one of the best resorts I stayed in the world. Its on Krabi?s Phra Nang headland and is only accessible only by boat, reached either from Krabi town or Phuket island. The 'luxury' huts were builts coconut trees. The resort is adjacent to three beaches, Railey Beach, Pha Nang Beach and Nam Mao Beach.
Take a boat trip out the other island, Koh Tao, Koh Gai etc. You might find that you and your friends are almost the only people on that island. Don't take a boat from the hotel though, if you are on the budget. I think on one of the islands, Koh gai or something you can walk from one island to another, the water is about 1 foot deep at most the whole way. magincal.
I think the bad reputations are for the area in town or in the city of Ao Nang itself.