The number one draw in Tulum, besides the gorgeous beach, is undoubtedly the ancient Mayan ruins at Tulum. I have been to a few of the other Mayan ruins in the Yucatan peninsula including the spectacular pyramids in Tikal, Guatemala (definitely worth the trip) and the interesting little ones like San Gervasio on Cozumel island. By comparison, the Tulum ruins are more expansive than I expected and the setting is by far one of the most picturesque. Think of ancient ruins atop a cliff, or the Big Sur of eastern Mexico. Walk amongst the ruins and imagine what it must have been like at the height of the Mayan empire; it is simply awe inspiring.
It is hot. Especially in August, you will feel the heat while walking the paths between the ruins. Make sure you 1) wear a hat, 2) bring sunblock, 3) bring water, 4) bring a small towel and 5) wear your swimsuit under your clothes so you can jump in the ocean at the end of the tour. There are no changing rooms on the beach, but there is a free and clean bathroom right at the entrance to the park.
There is a little train/trolly car that takes people to the front entrance of the ruins. It is only a few dollars and it is definitely worth it, especially in the heat. The ruins are quite a ways up from the parking area where all the tourist trinket shops are located. It is a round trip ticket.
All of the sites have little placards of information in English and Spanish.
It is a good trip for kids and families of all types. I saw several older folks walking through the ruins. Note, again, you should plan ahead with drinks and hats. There are some shaded areas, but there is no vending inside the actual park for water or sodas or to cool off. A small tourist shop selling sodas is at the entrance to the park behind the ticket counter.
Finally, if you’re lucky, when leaving the park, a man with a small cart might be there selling coconut, strawberry and lime paletas (Popsicles!) for about a dollar each. They are delicious!