The access to the roof has to do a lot in this plan: carry people up and out to the roof; stop the rain from coming in; provide shade; provide natural daylighting, hold a fan (or venting) for ventilation and somehow complement the design of the house.
Add to this a small platform and pole for a future zip line and possible rope bridge to nearby trees. Shown here are some concepts that would help us do all this.
To the right is Margy’s suggestion for a visual
inspiration.