A room with a view. Don't stay in the town. Head down to the beach and look for a place called Don Armando's. This is a shot from the sea front there towards the ruins. The cabins are concrete with palm roofs.
Alternative accommodation. The only problem is if Don Armando's is full. The next place along has very dodgy cabins as you can see from this shot. They are made from sticks of wood and all kinds of creatures wander through them in the middle of the night.
The ruins at Tulum. You can walk along the beach and up the cliff to get to the ruins. The only problem with this is you will be a long way from the main entrance and will not be able to get a guide. But then if you have a good guide book you probably won't need one.
By the main entrance you will find this pole and if you are lucky there will be some locals spinning around on it.
View in frame.