I'm very interested in the very earliest kings, those even before the first unification. Not to mention the development of Egypt into a major kingdom and the groundwork laid in all areas of government, military, etc. - pretty much all areas. It's really too bad none of the temples or palaces from these periods survived, I would have loved to truly see what the niched facade looked like in comparison to later construction. Just from the reliefs of the serekhs it looks like it would have been breathtaking.