Upon your arrival by boat you will be surrounded by locals offering to take you around town to see the sights. There aren't that many but if it's a bit rainy like it was the day we arrived, it's probably worth it to hire a tuk-tuk to take you around because (a) they know exactly where they are going and (b) some of the sights they take you to aren't exactly within easy walking distance. Keep in mind also that in order to get anywhere in town from the boat landing, one must walk uphill. We were originally told that it would be 150 quetzales per person for the "tour" but we negotiated them down to 90Q. They took us through town to El Mirador, the Parque de Paz, the site of the 2005 mudslide, the home where Maximon was to be found, and the Iglesia Parroquial Santiago Apostol (see my tips on each). At each stop we were given a brief description of the significance of the site although it helps if you have a decent knowledge of Spanish.
The tour ended at the church but it's a nice downhill walk from here back to the boat landing. And by the time our tour ended the rain was subsiding and the sun was out by the time we returned to the boat landing.
Fondest memory: Roaring through the streets in our tuk-tuk from site to site while on our tour.
Favorite thing: My buddy Ryan were in Santiago Atitlán for less than two hours, but it was a fun and focused time. We were on a mission- our main motivation for visiting being to visit the infamous Mayan "saint", Maximón. Having read about him in my Rough Guide, it was cool to make the experience a reality. When we got off the boat we were already expecting some kids to approach us and offer to show us the way, and in fact, they did. We somehow thought that would be cheating, but we still ended up asking at just about every corner, "Donde esta la casa de Maximón?" It was kind of surreal stumbling through the hilly town not sure if we were getting warmer or not wondering if we'd have time to visit Maximón and to make it back to our boat on time. The actual experience of visiting him really wasn't a big deal. I wouldn't say it was disappointing. It was just kind of bizarre. I mean, it's not everyday that you see a wooden deity smoking a cigar and being guarded by two solemn looking Mayans. However, in retrospect, I'm really glad that we did it. It's just one of those things that you'll feel good about after the fact.