Krabi Boat lagoon is a 20 mins drive from Krabi airport. You wouldn't be able to get the local taxis which only cost 150 baht to areas like Ao Nang. Instead, you will have to hire a private taxi which is 600 baht one way. The hotel can book your return to the airport at the same price. (It would be great if the lagoon provides free transfer).
The lagoon is deserted so what we did was ask our driver to stop my a 7 eleven which is equivalent to a department store. There are 2 restaurants in the compound, not much of a variety but good food. Breakfast is provided. (standard American breakfast.) You can't order in from the local food deliveries as well (ex. pizza hut, 1112).
The place is good, breezy in December, quiet, and relaxing. You can hire boats to bring you for sea rides although this may be costly, you should check as we didn't. The view is decent, and couples or even families will find it great. Families may hire the boat, or swim in the swimming pool.