Our please has 2x6 @ 24" in the exterior and 2x4 @ 16" on interior. Wall depth is 16" with 3" closed foam and the rest dense packed cellulose. The ICF foundation links up to the wall foam. Studs don't line up much. Windows are fastened to the interior of the 2x6.
Thermal mass; 1st floor is 5" crete, 2nd floor is hardwood. Each room is a different species since they are leftovers from a local mill. I looked up the thermal mass by species and choose that goes where based on that. Interior window sills are deep and long. I did 3" crete counter top type slabs for each.
A key part that was overlooked was the interior designer understanding the thermal dynamics. Once furniture, rugs, and other got in alot of the direct solar gain was lost.
