Mesa Verde

Mesa Verde, Spanish for green table, offers a spectacular look into the lives of the Ancestral Pueblo people who made it their home for over 700 years, from A.D. 600 to A.D. 1300. Today, the park protects over 4,000 known archeological sites, including 600 cliff dwellings. These sites are some of the most notable and best preserved in the United States.
Yeah, great 4,000 sites, but many of them probably only have a broken pot or two. The real draw here isn't quantity so much as quality. They have about 5 pretty darn good sites here. The largest and most famous of which is Cliff Palace (see picture). There is a snag though. This site is only accessible through a guided tour, which is probably cool, but freedom is nice as well. Anyway, I think Cliff Palace is a must, and the tickets for the tour aren't too bad at $3 a piece. They describe the tour this way:
Cliff Palace
Mesa Verde’s Largest Cliff Dwelling This one-hour, ranger-guided tour involves climbing five, 8-10ft (2.6-3m) ladders, on a 100ft (30m) vertical climb. Total walking distance is about 1/4-mile (400m), round-trip. The tour begins at Cliff Palace Overlook, an 8-mile (13km), 20-minute drive from the Visitor Center.
There are two other good sites that allow self-guided tours on. These are a bit smaller, but I think we should find the time to squeeze them in as well. These are known as Spruce Tree House and Step House. Step House doesn't open until Memorial Day though, so depending upon when we end up in the park we might miss it (although they probably mean memorial day weekend).