I've already gotten the boring exterior walls up on the south and west sides and then distractedly started working on the walls for the huge interior halls.
I realized I need to make the exterior 1 block further than my outline so there's room for the interior walls - which led to me putting up dummy walls of white concrete as a placeholder, but then the color (or lack thereof) annoyed me and I wanted to have something nicer looking. Picking the right combination of blocks to get the colors right is horrible and I need to let it go for awhile.
Tonight I'll get back to the task at hand of the exterior. I'm feeling good about Phase 2 taking less than a week as long as I can get a decent amount of build time in - maybe 8 hours total?
I'm pretty happy with the color scheme for the exterior - once I found that "bone block" is a thing. I'll have to bring in some more elements like iron blocks for some of the more modern sections and I'll still need to decide whether to go with tinted or clear glass. The other consideration is doors - should I just leave the doorways open? I think I'll definitely want real doors inside and will want a mod that silences them.