Okay. Let's try this. Here's a list of the 20 largest cities in Switzerland as per Wikipedia:
Zürich
Geneva
Basel
Lausanne
Bern
Winterthur
Lucerne
St. Gallen
Lugano
Biel/Bienne
Thun
Bellinzona
Köniz (statistically only the whole municipality, but not the village)
Fribourg
La Chaux-de-Fonds
Schaffhausen
Chur
Vernier
Uster
Sion
Now I'd be happy to carefully find all the correct coats of arms and spread them out inside an outline of the country, but here's a map showing where the largest cities are actually located:
Ian says, "form follows function: the actual location of a city on the map is irrelevant, as long as it makes sense relative to the others." Fine, but I honestly don't see how I can both spread these cities out AND have them make sense relative to each other. I'd have to place too many of them south of the mountain chain when in fact they lie north of it. That's why my attempt above included so many ski resorts. Would you move St. Louis to the other side of the Rockies?
A suggestion: south of the mountains I use mainly ski resorts and two of the largest cities there, north of the mountains I use the twelve largest cities there, spreading them out as necessary. Since ski resorts themselves don't have coats of arms I use whatever makes the most sense, either a city or canton for which they are named or in which they are located. Please let me know if this is acceptable. If it's not, please consider the next suggestion...
#2: According to the list and map, just four of the largest 20 cities lie below my mountain chain: Lugano, Chur, Bellinzona and Sion. So I map just four terts in the south and fit the other 16 north of the mountains. I'd reduce the number of "passes" through the mountains to just two. This will mean having to make the map larger to fit those 16 in an area now occupied by 12. It will also make the mountains less relevant -- the map won't be so effectively broken up into two zones. This will affect gameplay.
I think option #1 is much better, but if mixing resorts and cities is no good, #2, weird as it is, seems at least slightly reasonable. I think it will make for a strange-looking map and I think the gameplay will suffer, but I'd be willing to do the graphics.
If neither option is acceptable I'd be more than willing to consider any specific suggestion. Switzerland is an unusual country, with most of the mountains in the south half and most of the development in the north half. It makes it difficult to translate into a CC map. Some rules or preferences will have to be stretched or adapted.