Since we're doing general building suggestions in here as well, here's a little something that helps me out a lot: Try to break up those straight, flat walls a bit. Maybe add a column offset by 1 block every 5ish blocks, add a protruding ring around the towers on every floor, things like that. Just something to get away from the solid single-colour walls. Just don't get crazy on the contrast, Columns might work with basalt or xychorium bricks for example, stone brick could work but might already clash with the netherbrick.
Sorry. Could you possibly show me some pictures of what you mean? I'm terrible at interpreting things over the internet. I'm more of a visual person.