Someone else has posted on here about reserving a private van with a driver for a smaller group tour. That option allows you to leave very early, tour Chichen Itza in the morning and then head back. It's a two hour drive by hgihway from Cancun. It is truly worth it. To Tulum most people pair it with a trip to another location while down south. Usually people do Tulum and Xel-Hal or Xcaret. You can do the same with a private van and spend an hour or so at Tulum then head to Xel-Ha or Xcaret for snorkeling and fun.

Cheryl