I just answered this forum post on TripAdvisor and thought it might be useful to post it here as well.
You can be done at 11:00 AM when starting there at 08:00 AM. It is recommended to schedule your arrival 10 minutes before 08:00 AM, especially during the high (holiday) season, since cars are lining up at the entrance. Buying tickets, going to the restroom and getting a local guide will take you another 15-20 minutes. The local guides are usually take 90 - 120 minutes, some of them even a bit longer, depending on your interest. If you need any recommendations in regards to a local guide, feel free to contact me.
After leaving Chichen Itza I am recommending to take the toll road (Quota) to Playa del Carmen, which is the fastest way to get there. It will take you two hours to Playa del Carmen.
You most likely willl be hungry. I enjoy the following restaurants: Clorofila - Green and Vegan, Don Sirloin (typical Mexican tacos), La Perla Pixan (traditional Mexican), Los Aguachiles and Las Hijas de la Tostada (seafood), La Cueva del Chango and Papa Charly (a bit of everything).
The down town area is pretty much centered around the 5th Avenue, which is worth for taking a walk and enjoy an ice cream or a coffee, but mainly is about shopping and restaurants.
In Playa del Carmen you might want to visit the "Parque de Fundadores" with the Portal Maya, the "Voladores de Papantla" and the first chapel of Playa del Carmen "Nuestra Senora del Carmen" Church. Try some fresh fruit from the local vendors.
If you let your car close to one of the restaurants everything above mentioned is in walking distance and you might want to consider to walk back on the less crowded 10th avenue, since it is as well a nice walk where you can see some street art.
That should be enough for your 3 hours. Have fun and enjoy! #playadelcarmen #streetart #foodie #traveltips #pdc #rivieramaya #mayanriviera #rivieramayalovers