I would like to see Ft. William Henry just for the historic value but I will take your advice and skip it if it costs too much.
Well, I used to live up in the Lake George area, and although it is a complete reconstruction, Fort William Henry does show the original excavation and a pretty good historical narrative of the French and Indian War. Also, visit the marker up the road for the Battle of Bloody Pond (as seen in the Last of the Mohicans).