I have a couple different floor plans worked out, here is the front elevation. To the existing house ...
* "Enlarge" the middle section. Existing roof on this section can stay in place minus a dormer cutout. Add same pitch (4:12) roof at same elevation, narrower on front and back by about 2'. The "gable inside the gable" is the existing roof, the enclosing gable is the new.
* Drop garage ceiling to the left of the right side-load garage door/opener mechanism to 7'6" (as drawn, not that you can tell), or 7'0" (need to check code, would rather have those extra inches upstairs) all the way across (front-to-back). This creates a 22'x14' space for master suite.
* Interior, non-bearing wall work to create access stairs (31" or 25" difference, depending on height garage floor is dropped to, assuming 10" floor thickness) to new master suite.
Also, this drawing uses the existing siding, except on the front of the middle section and gable-end shingles. We found some extra siding in the garage attic, plus we should be able to salvage enough (won't take much) to do repairs (a few small holes, a little melted from idiot former owners' gas grill). Cultured stone accents would be new as would be the gable-end shingles.
I'm not looking for exact numbers, just "would cost more, less, same" type info.