Some extra thoughts
Tulum is a bit expensive place. Even with European standards. The food is pretty cheap but everything else is pricey.
You can find beautiful, handmade clothes, bags, home decor, and other accessories with a bit steep prices. If you want that hip feeling and handcrafted souvenirs that are not from like the mainstream tourist shops, be aware open your wallet.
Clothes are mainly done with good quality materials, linen and leather are used a lot. One item that I was really into was a huge dreamcatcher but our suitcase was too small for that. Next time, next time...
With regards to shopping (and if you are not so much into those expensive Tulum beach shops) try Tulum centre instead. It has small inexpensive shops selling souvenirs and local handcrafts. There are lots of leather sandals, hammocks (I wish I could have bought one of the beautiful lace hammocks), dresses, jewelry, dreamcatchers, and pottery. You have to bargain to get the best price in those shops.
And if you are thinking whether to rent a car or not. I highly encourage you to do it. Driving in Yucatan is easy and we didn't have any dangerous situations or anything like that.
Pack your flip flops or buy them from Tulum. If you are staying at the beach, you don't need even the flip flops. We were most of the days just barefoot.
And remember that in many places and hotels in Tulum, you cannot flush your toilet paper but you should put it into a separate waste bin instead.
Remember to visit at least Tulum Ruins but I can also recommend Chichen Itza with a kid. It's easy to combine a night in Valladolid with a visit to Chichen Itza.
We will definitely go back. It is just a matter of time and money. As a conclusion, I'd say that Tulum really surpassed my expectations with everything. It became one of our dream destinations!