The quick answer is 10 hours and 31 minutes according to Google Maps.
That would make two days I guess stopping half way, but there are just so many options depending on how long you have to spare.
I would prefer to take a route with limited motorway and include some great roads on the way, you could cut through the Vosge Mountains, across the Black Forest and take in a number of Alpine roads as Austria is the far side of the Alps from Calais.
Ig taking a French route I would do the first 150 - 200 miles on the motoray and clear the clutter / more boring North and set yourself up with good roads from day two.
Dunno how far you have to go to reach the tunnel, but...
Assuming a few hours I would suggest maybe a stop at Two Wheel Moorings near Verdun. You could also go a bit further and reach Nancy or Epinal and be on the edge of the Vosges moutains so day two starts off much better.
From here you could whizz through a bit of the Vosges to Belfort and then on to Bern taking you into the Swiss Alps, Past Interlaken and if the weather is good drop down the Grimsle Pass and over the Furka Pass (two of the Alps finest) to arrive in Andermatt. Depending on where you stopped in France you could be here around lunchtime and go for a blat up the Susten Pass, or down the Tremola (or do the Furka, Nufenen and St Gothard / Tremola in a loop)
From here it is another easy day to your destination heading towards Chur, then taking the road to Davos and then onto your destination - all on amazing roads.
That is a 3 day trip, but two of them would be fantastic.
For a two day option I would suggest a big Motorway day to the Black Forest (try Pension Williams) if your close enough, or stopping a bit shorter (say Metz) and then you can run through part of the Black Forest (follow aa line Strasbourg to Konstanz) along the North bank of the lake (the south bank is quite built up and congested) and then your almost there in two days with just one dull day.
I am sure others will know of alternate options, I have just listed a couple of possible routes I can vouch for from personal experience.