You can also walk the "streets" of Colonial Williamsburg, all the way down. That will be free. You can still stop in the little shops, eat at the Taverns, enjoy those in costume, and admire the buildings from the outside, without paying admission. You don't have to pay for this. Now, if you really want to absorb the history, it is totally worth it to see the insides of the mansion, the magazine, the house of delegates etc. Just depends on how much time and how much $$ you would like to spend.