Hello Martin,
Last summer we had a trip to the Como Lake:
In France I stayed in Munster (Alsace) Hotel Verte Vallée.
There you have the interesting "Route des Crêtes".
Our hotel in Switzerland was not good but a friend can recommend the Hotel Bellaval in Scuol.
At Como Lake we stayed in the Hotel Lumin in Cremia.
On our return through the black forest we stayed in Badenweiler Hotel Morgensonne.You can also visit Baden-Baden. There we stayed in the Hotel Merkur.(Badenweiler to Baden-Baden via the Schwarzwaldhochstrasse)
Many greetings.