The attic already has walk up stairs.
And the 3rd floor already has open web trusses engineered for live load bearing weight, so at least that won't be a huge undertaking. It also has electrical circuits that can be tied into easily.
I will also be adding a 8x5 bathroom (left) and large closet (right). The plumbing for the bathroom will tie into the 2nd floor bathroom which is almost directly underneath.
There are some cool funky spaces as well that I will finish to get those neat sloping areas in an attic, once I move some of the duct work. These areas are only partially load bearing at the moment, so I will have to reinforce those areas a bit by sistering 2x10s to existing joists.