We live about a mile down the road from Greenfield Village and have annual passes--we go many times a year, and there's always something interesting happening. Spring planting with horse-drawn plows, a Civil War reenactment, a baseball game circa 1900, preserving food for the winter at the Firestone farm...
Also a very relaxing place to go--you know the modern world is just outside the village, but that's hard to believe when you're there. Don't miss the July 4th fireworks (held for 4 nights with music by the Detroit Symphony Orchestra), and make sure you stop by the Eagle Tavern and order a drink from Silas, the barman. (""Temperance drinks"" available, too!) The tavern is straight out of the 1850's, and so is Silas. He loves to discuss ""current events"" of the day!
Lots for the kids to do, but plenty of fun without kids, too.
Pros: Lots of activities, Recreates history wel, Coolers, wagons okay
Cons: Sometimes crowded, Long lines for food