I was there a few years ago for work and had a fantastic time! First tip, you're going to need $10 cash for each person to get in the country. I'll make a list of some of the cool places I went and I already reached out to my buddies that live there to get some add'l ideas. One place I highly recommend going is Los Planes de Renderos. It's an area on top of a mountain with a bunch of "pupuserias", small diners that make pupusas.