Why not think about a round trip -
Channel Tunnel, turn left to Belgium, and onto the City of Luxembourg for 1 night.
Next day head south towards, Strasbourg, turn left into Germany & head south with the Rhine on your right to Switzerland - head for Luzern for the next night ) a pretty little lakeside city.
Next day head south towards Italy & Lake Como via the 10 mile Gottard Tunnel (3rd longest road tunnel in the world), stay the night in the town of Como.
Next day head south through Milan to the Med, turn right and along the coast is Portofino - a fabulous romantic place to stay
You can then head along the coast into France and onto Monaco, you could then come back through France to Paris.
We did the trip down to Portofino but then continued further through Florence, Sienna, Rome to Naples, Sorento & the Amalfi Drive a few years ago - we tended to do very long drives of 500-600 miles per day - quite easy if both of you drive.
Not exactly what you asked for, but worth considering
One of the advantages of the non-France route is that the motorways are free (except Switzerland, which charges a fixed fee for a year) - Think it cost us at least £90 for the tolls form the south of France to Calais