I prefer to use materials that would make sense for the structure (wooden, brick, or stone roofing for example.) instead of just going for color (No coral in roof for the color.). The main reason for no texture packs is because I will be copy pasting the rooms together into a single world. Having multiple texture packs could get messy. That goes for add-ons too. (Too much stuff would over complicate things for me, as I will be the one putting the castle parts together. Could also cause errors.)
Sorry if my comments are a bit too long. I'm still getting used to actually posting stuff publicly, and I'm not the best talking to people.