Good afternoon,
I'm planning a trip to Thailand with my family and the last days we are flying to Phuket and returning from Krabi. To go from one place to another, we are thinking about taking the ferry to Phi Phi from Phuket one day, spend the day there, and take the last one to Krabi or Ko Lanta, depending on our hotel.
Do you think that's a good plan? Is there any luggage store in Phi Phi where we can leave our luggage while visiting the island this day?
Thank you very much.

When you arrive in Tonsai, the main village you will see many shops and restaurants where you could try to store your luggage. But I would ask with the ferry boat company that you take, they might be able to store your luggage while you are on the Island. I think it should not be a big problem.