The shed is almost 7' on the edges, the addition is getting 9' ceilings on both floors, so sayeth the wife so it shall be done.
It's all 2x6 exterior framing, not that much more expensive and the extra insulation should save enough electricity to offset the extra cost pretty quickly. We only plan to live in it for a few years but, the structure will stay as a guest house when we build a permanent house. Plus, you never know what the future holds.
I cheated on the window header because it's 2x6 and the studs are doubled up or very close. I should probably change it, it's one of those things that'll probably be fine but isn't technically right. We're using the same metal siding that's on the shed and a corrugated metal roof so there's less weight than there would be with Hardie and composition shingles and there will be an interior wall 6' from here that the load will get spread to. It's just a stairway landing above that window.