By going into the DMZ, do you mean that room with the guards inside that you posted a picture of?
Ok, I checked back with the tour company that I reserved with and they do offer another tour that goes into the Joint Security Area but it's a full day tour so I won't be able to do that because of my flight and also more importantly, we're traveling with our daughter and children are not allowed in the JSA area.
So the sites that I would see with my current tour are: Imjingak Park - The Bridge of Freedom - The 3rd Infiltration Tunnel - DMZ Theater & Exhibition Hall - Dora Observatory - Dorasan Station - Pass by the Unification Village - Amethyst/Ginseng Center
Worth it to still go or better off doing something else in the Seoul area? I'll have more or less the entire previous day to see Seoul.