Hi Patti,
Happy for you. For Chichen Itza I’d just catch a taxi.You can ask the bellboys to get one for you or walk across the highway (via tunnel) and negotiate with a driver to do RT.
For Xelha or Xcaret I’d jut get there on my own via taxi or colectivo and buy a ticket there. You can save about 10% by booking ahead but I never know whig day I might want to go.
For ATV I’d book with a reputable company at a price I was comfortable with.