The first thing that springs to mind is Ronald Wright's excellent Time Among the Maya, which chronicles his travels in Belize, Guatemala, and Mexico at the height of Guatemala's civil war and during the build-up to the Zapatista uprising in Chiapas. It's a wonderful travelogue, but what really sets it apart is Wright's impressive knowledge of Maya ethnographic and archaeological literature (as it stood in 1989, of course some things have changed since then), which lend his observations a degree of richness, cultural sensitivity, and historical scope that most travel writers simply can't produce.
If you're interested in archaeology, Michael Coe's The Maya (8th ed., 2011) is an accessible introduction and it's compact enough to travel with.
Incidents of Travel in Central America, Chiapas, and Yucatan by John L. Stephens is a classic of travel literature. He and the English artist Fredrick Catherwood traveled extensively in the area in the 1840s and wrote the first European accounts of some now-famous Maya ruins. The books are worth picking up for Catherwood's wonderful illustrations, but you can read the text online for free: http://en.wikisource.org/wiki/Incidents_of_Travel_in_Central_America,_Chiapas_and_Yucatan
There's a great book shop in Antigua on the west (right-hand side when you're looking at the volcano) of the plaza. They have a huge and well-curated selection of travel, anthropology, and archaeology books in English.