If you have any flexibility in your plans, as a history nerd it might make sense to delay your trip a few weeks to the Patriots Day weekend instead (April 15-17). That's when the "big grass field and a few statues" in Lexington/Concord will be a lot more interesting since they have battle reenactments and other events to commemorate the anniversary of the battle itself.

Not sure how committed your plans are, but given that it's only three weeks after your planned trip and you're coming here for the history, it might be worth thinking about if you can do it.