Neat design for your house. I'm somewhat partial to homes with towers!
I like your take on the tower config, and the widow walk. What kind of stair do you have planned to get up there?
Note on the round top windows: I love them and have them on all of my windows. Just be aware that the semi circle windows are quite pricey, and trimming them inside requires expensive milled wood, or special materials like FlexTrim, to match the curvature. I used FlexTrim, and it worked out great, and accepted stain well to match my other woodwork.
I'm looking forward to reading about your house in Domes In Progress!!!