Belize. Go there. Stay. It's amazing.

Palenque, Yaxchillan, Bonampak and San Cristobal at a minimum

two weeks is not enough for only Mexico! If you don't want to spend the half of your time in Buses, go to Merida. From there you could do a lot of different trips! Beach, Cenotes, Ruins... But my favorit place is Zipolite, south coast of Oaxaca... beautiful beach and cheap compare to Tulum, go to the amazing dolphin, turtle, fishing and snorkling tour! But Tulum is also nice for some days. Stay in the hostel "Lobo Inn" and have fun!

Palenque, Mexico and Tikal, Guatemala are must sees!

there are soooo many things to see in south mexico... go to cancun (tourist-stlye) but also you have to go to Playa del Carmen (30 min. drive from Cancun), its much better... and go to Tulum, great beaches... lights go off at 10 in the night so you have a quiet, relaxed and perfect view of the szy and the stars

Stay in Mexico and come back for Guatemala next time you visit. So much to see in both countries, but the best food and culturel experience I would say you find in and around Oaxaca. If you want some beautiful beaches go to Yucatán and visit Tulum while it's yet not spoiled by the tourism like Playa del carmen and Cancun.

southeast Mexico (Chiapas, Oaxaca, Yucatán and Quintana Roo)

palenque, tikal (it is possible to do it by bus, boat and bus), then flight to guatemala city to go in Antigua. Then Quetzaltenango and Atitlan lake and go to San Cristobal. Finish with Canyon del Sumidero close to Tuxtla Gutierrez.

Ditto on the San Cristobal de la Casas. Was just going to be an overnight stop and spent a week there. Beautiful!

Mexico!

San Cristobal in Chiapas + Panajachel and Antigua in Guatemala

Lake Atitlan - Guatemala for sure.

mexico !