I have decided to go with the 3rd design option. The core is pretty much decided. It will be a heavy pier that houses bathrooms, stairs, elevators, and mechanical shafts.
The ground floor is a void space where the core anchors to the ground, and the other supports. I am currently thinking it will be a large circular support, a forest of columns, or an exposed truss. shown below.
The 2nd Floor will be used for offices for a sustainability commission.
The 3rd Floor will be the exposition area. It also houses the atrium which will be a double heighted space from a void in the 4th floor
The 4th floor will be the cafe and children’s discovery center.
The Roof can act as an outdoor terrace.