Agreed. The "holy grail" permits are Arizona, Utah, and Florida (recognizing that there is significant overlap between the 3.)
The rest depend on what state in which you reside.
For myself, I would need the following permits to get as many states as possible:
Massachusetts (where I reside) - GOT IT
Utah - GOT IT
Arizona - GETTING IT
(I don't have the rest...but we're talking "in theory" so here goes)
Florida
Maine
New Hampshire
Connecticut
Rhode Island
New Jersey (fat chance, but possible in theory)
Oregon
Maryland (not likely to get, but possible in theory)
South Carolina (non resident permit only if you own property there)
If I had these 12 permits, I would be able to carry in every state except:
New York
Colorado
California
Hawaii