To close out an evening after an island tour without much travel, start by comparing Let's Relax Spa Wake Up Ao Nang. It sits in central Ao Nang, walkable from most hotels, and offers a range of programmes including aroma massage and two-hour courses, enough to fill a relaxed Christmas evening.
If you would rather not leave the resort, check Let's Relax Spa - Centara Ao Nang Krabi and Let's Relax Spa - Centara Anda Dhevi Krabi. Each operates inside its namesake resort, so guests can book without a transfer, though couple-room availability differs by property and is worth confirming ahead of time.
For a day on land without an island tour, look at Wareerak Hot Spring & Wellness. Combining hot spring bathing with massage gives you a way to fill a day of the trip regardless of the sea conditions.
If the chain spas in central Ao Nang are full at your preferred time, keep Radarom Spa Krabi in mind as a backup. As a local spa covering Krabi town and the Ao Nang area, it offers a different price point from in-resort spas. Since Christmas is peak season for popular time slots, reserve an evening or sunset appointment well ahead of your date.