Been to Mexico many times & have done most of the excursions so here's my take:
Xplor, Xel-ha &X-Caret are all great for fun/active excursions. They are pretty similar but have some differences so it really depends on what you want to do. This website shows what each has to offer:
http://en.xcaretexperiencias.com/xcaret-xelha-xplor-tour.php?gclid=EAIaIQobChMI9bmsmPX11wIVDI9pCh2lygulEAAYASAAEgK2avD_BwE
Tulum was neat because it's the only Mayan ruins that are on a coast, it's fairly small though (compared to Chichen Itza) so I would only really recommend it if you are near by. Chichen Itza was cool but it was better when you could still climb on the ruins.
Cenotes are cheap & easy ways to spend a day swimming & hanging out. We always try to spend at least 1 day/afternoon at a cenote. Most resorts we've been to, offered some kind of box lunch so we can bring food a long with us.