Traveling with kids in Guatemala is an experience not to be missed! Some suggested activities are:  walking around the folk art markets, eating in the many wonderful restaurants, and finding historic sites.  You could also take a day trip  to Chichi market, it is possible to arrange for a  private van to take a large family.

Check for recommended hotels on trip advisor and other such sites, then look at their web sites (even the smallest hotels have web sites and most have 800 numbers), and contact them DIRECTLY. It is important that you have the accommodations you want for your family to be comfortable.