Krabi is stunning. It also is very isolated. When I say it was a trek to get there, I mean it. Our hotel was only accessible by boat.
We stayed at the Centara Grand. 5 stars and home to many monkeys!
Explore the beach caves, tan, swim, and relax. I really enjoyed Ao Phra Nang Beach.
We rented a speedboat and sailed about an hour away to Koh Pi Pi, and pulled in at a quiet cove to go snorkeling. On our way back, we pulled in at Maya Bay - the beach made famous by Leonardo DiCaprio. It was way too crowded with tourists (mostly Chinese) so we didn't stay long. I am so grateful that the government has since shut this to restore the ecosystem.
If you're a James Bond fan, try to see Khao Phing Kan aka "James Bond Rock"