Tuxtla Gutiérrez [1] itself it worth a day—time enough to visit the zoo and a museum or two, then while away the evening at Parque Marimba [2] or a bar. Chiapa de Corzo [3] and Cañón del Sumidero [4] warrant a full day too, but can be done as a day trip from San Cristóbal [5] if you’re based there.
Sima de las Cotorras [6], El Aguacero [7], and the Ruta Zoque [8] are all on the far side of Tuxtla away from San Cristóbal (and best visited with a rental car) so an overnight trip makes more sense. Of the group, Sima de las Cotorras has the best accommodations, and if you stay the night you’ll be there when the parrots come and go, in the evening and early morning.
Links:
[1] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez
[2] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez/sights/parque-marimba
[3] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez/chiapa-de-corzo
[4] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez/around-tuxtla-gutierrez/parque-nacional-canon-del-sumidero/canon-del-sumidero
[5] http://www.moon.com/destinations/chiapas/san-cristobal-de-las-casas
[6] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez/around-tuxtla-gutierrez/sima-de-las-cotorras
[7] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez/around-tuxtla-gutierrez/el-aguacero
[8] http://www.moon.com/destinations/chiapas/tuxtla-gutierrez/ruta-zoque