This route looks compact on a map, but each move combines hotel pickup, a road or boat leg and another transfer. Plan the exact chain before booking three separate stays.
Use Phuket for the widest choice of flights, neighbourhoods and land-based alternatives. Use Krabi or Ao Nang for limestone-coast trips and Railay access. Use Koh Lanta for a slower island stay rather than another rapid excursion base.
If the trip is short, remove one stop. Repacking and waiting for transfers can consume more useful time than the geographical distance suggests.
Confirm pickup location, departure pier, arrival pier, luggage rules and the road transfer at the far end. In the southwest monsoon, roughly May to October, TAT advises that ferry conditions can change quickly and some island services may stop.
Keep the final night near the airport or on the mainland when missing an international flight would be costly. Never rely on the last theoretical boat connection without a recovery plan.