Previous reviews have thorough historical information about Chaco Culture, so I will focus on logistics and what not to miss. I went with a group of five plus our wonderful tour guide, Mo, out of Santa Fe. It is a 3-hour drive from the city and very much worth it. I enjoyed hiking at Una Vida, particularly to see some very clear petroglyphs. Chetro Ketl and Pueblo Bonito were my favorite sites, particularly the latter because of our park tour guide who took us through there. He was very knowledgeable about Chaco and had been working at the park for 10 years. What drew him to the area was the gathering of fellow astronomers, who gaze at the clear night sky because there's no light pollution.
It can get very hot at Chaco Culture. I was happy that Mo told us to bring a light long-sleeved shirt to protect us from the sun. If you plan to travel from Santa Fe, I highly recommend going with Mo's tour group. You can find more information at www.swadventures.com. I wouldn't drive to Chaco myself, especially on the washboard road from the highway leading into the park. Also make time for the gift shop, as it has wonderful books and other high quality souvenirs. Beside the gift shop is a small museum, which is also worth a visit. I especially liked the diorama it had of what Chaco Culture could have looked liked when it was inhabited. It gave me a clearer idea of how the present-day ruins would have once functioned.