Just got back from a trip to Guatemala. Here are a couple tips… Tikal ruins are incredible, but stay over night in Tikal so you’re able to visit the park in the late afternoon and first thing the next morning (6am is best for monkey viewing). Otherwise, if you take a tour from Flores, visiting the ruins becomes more like a Disneyworld experience.
Lago Atilan is amazing…If you stay in Panachel, make sure to at least take a water taxi across the lake to visit (or stay) in the other towns. It’s a beautiful ride. I stayed in San Pedro, which I’d only recommend to backpackers to stay overnight… might want to check out the other town with Atilan in the title. The Sunday (or Thursday) market in Chichicastenango is a must see/do.
Semuc Champey is supposed to be incredible…I missed out. Don’t bother staying in Guatemala city… Antigua is much nicer and safer. (Great Saturday market there) As far as hotels and other details I suggest picking up a Lonely Planet or Rough Guide. Didn’t make it to Guatemala beaches… visited the ones in Belize instead, which were incredible.