Phi Phi anchors the classic Phuket island route. Phi Phi-Khai-Pileh-Maya by Speed boat (SeaStar) covers Phi Phi, Khai, Pileh and Maya in one day, while 1 Day Trip Phi Phi - Bamboo Island Tour by speed boat (Seastar) adds the Bamboo Island side. Both are full days, so place them on the second or third of the four days and keep buffer either side.
If snorkelling and time in the water come first, compare Racha Island Daily Tour, run as a Korean-only trip with free underwater photos and an intro dive included, which suits a first diving experience with less briefing-language friction.
For a quick trip to a nearer island, Khai I Love You Half Day (PNT) is a solid default. The half-day format leaves the afternoon open, and the short crossing is relatively less exposed to swell, which makes it useful for an awkward slot like the first afternoon.
John Gray Seacanoe is a different proposition from a speedboat island day. Paddling into the limestone formations depends more on tide and weather than swell, and satisfaction is high when you want quiet scenery. NOAH Catamaran Yacht Tour is the option when you want the steadier ride of a larger boat.
For a land alternative, Hanuman World & Luge combines jungle ziplines with a luge, undemanding with children and with sections that run in the rain. [Last-Day Tour] Phuket Private City Tour & Airport Drop-off uses the time left after checkout and ends at the airport, solving the luggage problem while adding one more activity on the final day.
Before booking, confirm the meeting point and pickup, departure and return times, boat type, snorkelling equipment, meal and national park fee inclusions, minimum participants, age rules, and operation, refund or replacement terms under sea and weather conditions. Because cancellation is possible in the Chuseok travel period, read the refund terms particularly carefully.