Williamsburg is dominated by Colonial Williamsburg, one of the most ambitious living history projects in the world — 301 acres of restored and reconstructed 18th-century buildings staffed by costumed interpreters. But the city has more layers than the historic district alone: the College of William & Mary gives it the energy of a college town, Busch Gardens provides family entertainment, and the Colonial Parkway connects it to Jamestown and Yorktown.
Plan at least a full day for Colonial Williamsburg if you want to do it properly. The ticket price is steep but it covers multiple days; many people find that two or three visits across consecutive days is the best approach to absorb the scale of it.