Consider not booking one day tour unless your time is really limited.
I booked a day tour to Phi Phi Islands with overnight stay on Phi Phi Don.
We left first group just after lunch and joined another group on the following day also after lunch.
If you really want to admire beauty of this place, avoid one day trips. Book a ferry and stay there for few days. Rent a longtail
boat and enjoy surrounding islands at your own pace.
What a day tour provides:
You start from Phuket Island and after 45 minutes on a speedboat you reach little paradise in Phi Phi Leh - Maya Bay.
The natural beauty of this place is second to none and since The Beach movie was filmed here it is the most visited beach, making this place incredibly crowded. Unfortunately, if you choose one day trip, you won't have other choice than share the beach with
hundreds of other people. It is a shame they give you only 30 minutes to explore the place - a queue to the toilets takes more time. They do warn you that if you do not return on time, they leave without you. Boats can only dock at the bay for half an hour
and need to clear the space for other speedboats coming.
After stopping at Maya Bay, speedboat travels to Phi Phi Don but on the way there, makes 15 minutes stops in Loh Samah Bay for snorkeling from the boat, then at Pileh Cove
and Viking Cave where you can watch both places from the boat. Next stop is another famous place - the Monkey Beach where you suppose to spend some time feeding wild monkeys - unless you are unlucky (but no one warns you before departure) and tide is too high
covering all sandy parts. Then the only option is to watch the monkeys from your boat. From there, boat takes you to the Phi Phi Don pier, for an hour long break with lunch included and quick walk along the pier if you are interested. It is a buffet lunch
and I can't say anything positive about it, so run away and choose from many nice restaurants located along the walkway if you can.
Then, another one hour long speedboat rides back to Phuket with one additional stop in Koh Khai
Nok Island. A tiny island with beach restaurant and barbeque area, with nothing to offer except for swimming or snorkeling and sunbathing. The break takes about 2 hours and it is a waste of time if you consider that you have only 30 minutes at Maya Bay. You
have to pay for wooden, overused and old sun loungers, for toilets which are so dirty and awful, you will use them only in emergency (don't leave your flip flops on the boat - you will need them if you are brave enough and pushed to your limits).
In overall a one day trip only gives you an idea how naturally beautiful is area of Phi Phi Island. Thankfully we stayed there overnight.