[GWN7]

After looking at the photos, I think the best option is dormers. Expand the existing one and put one on the oposite side. That is if there was a dedicated stairway to the second floor already.

This would enable you to move the master bedroom to that space and add a second bathroom. It appears to be the most cost effective means of adding living space.

If you take the roof off and add a second story you will need to have the foundation certified that it will handle the extra load. Not to mention you will have to get approval to do so. Is there existing two story homes in the neibourhood? If not they might not approve the request. As there is a existing dormer you will get approval easier to add another one.

If you want to lower the ceiling height on the main floor (as per your first post) the roof will have to come off and you will have to gut the interior of the house. A new floor (for the second floor) will have to be attached to the outside walls which means rebuilding the ouside wall supports. Very expensive and very stressfull if you and your wife have to live in the basement like mole people for 6 months.