So I've been playing on a downloadable copy that bundles both games+patches, because it's simpler than going through the process of using both my original discs and applying patches. After years of reading instances of people playing without the expansion, I think I'm going to give it a try! I realized the Cleo missions and buildings don't really add much to the game, in my opinion. Something about the playstyle of the Cleo missions never ends up making me come back to them, except for Alexandria. There's the zoo, which is a 'meh' addition to the the entertainment system that actually introduces disadvantages. Some industries are added, but they are only relevant to monument construction. I think trade ships might behave differently in Cleo, and the Pharaoh behavior was marginally advantageous? Or was that a change that was made in a patch that applies equally to Pharaoh and Cleopatra? Plagues? Meh. What other differences are there? Perhaps I might keep two different installs if possible, to switch back and forth.