Our Resident Guatemala Expert Claire Tackles This One:
I traveled to Guatemala and Belize for 11 days in March. I wish I had tempered my zeal to see as much as possible with the realization that chicken buses take longer than you can possibly imagine to wind through the mountains. (And it was only a half an inch on the map!) Assuming you plan to spend eight days or so in Guatemala and based on your interests, I suggest you visit Antigua, Lake Atitlan and Tikal.
Take the two-hour shuttle ride out of Guatemala City to Antigua. There, be sure to watch the sunset at the rooftop Sky Cafe and spend at least one afternoon climbing Pacaya Volcano.
From the Antigua bus stop, head west to Lake Atitlan, surrounded by smoking volcanoes and indigenous towns. I stayed in San Pedro, where the gringo population outnumbers the locals. For a more authentic experience, take the boat from Panajachel, the main port, to other villages dotting the sunken volcano. Santiago has a popular music scene and local Mayans praying to a statue of Maximon, the saint who loves to drink and smoke.
From Atitlan, head north to the Mayan ruins of Tikal. If possible, I recommend flying there and back to Guatemala City--otherwise you'll lose two full days to travel. Take a morning tour, watch the sunrise from the temples and listen to the hoots of the waking howler monkeys.
Yep, that's just about the best week I can imagine--and the one I would plan for myself if I could find time to step away from my keyboard for five minutes. Have fun!