We decided to check out the beach at Railay and not do a tour.
It is ridiculously easy. You got to the beach (any hotel will tell you). You can't miss the ticket stand. It will be 200B for a return. You climb into a long tail boat when there are enough people waiting to fill it.
This could mean you wait a while but we were lucky. We waited about five minutes and got ours. The boat takes about ten minutes I think. I wasn't watching the time and it felt like a fast ride.
You will get a little wet from splash but it's not much.
Railay beach is beautiful and small. If you are staying there it is quiet and looks popular with couples, young and old, and families.
There are trees along the beach for some shade. There are a couple of places you can eat and a general convenience store. Other than that there is not much to do. It was lovely to relax on the beach.
The last boat from Railay is at 6pm and it's the same thing to get back. You give your ticket to a guy at the boats and he will direct you to next boat leaving for your destination.