Mayapan is one of the three most important Mayan sites in the Yucatan; the others are Uxmal and Chichen Itza, which are much more over run by tourists, especially the latter, which is a mess with the vendors and the hordes of red-faced tourists from Cancun.
While Chichen Itza is crowded and Uxmal is very popular, Mayapan is completely silent and relatively un-visited and you can enjoy the site in all it's quite majesty. If you get local guide Eric to give you a tour (about $200 pesos) you will be treated to a passionate explanation of the site and why it was important.
The trip takes about 90 minutes of driving, which will be around the city of Merida and along a route that allows for stops in little villages along the way to admire churches and other attractions like a cenote in the center of the town of Telchaquillo, for example and it's austere but rather interesting church. These can be visited on the way there or on the way back, depending on your time constraints and level of interest.
At Mayapan, you can still climb the main pyramid, which you can not do at either Uxmal or Chichen Itza and get the fantastic view as seen in the photo on your left.
Highly recommendable and enjoyable!