Just came back from that part of Europe about a month ago, I could never understand why people avoided Switzerland, used to work there, so thought Id cough for the 40 euros and ride through it.. And I was impressed to say the least.
Coming in from the Basel side, id motorway it down to San Gottardo, then take the pass up the mountain.. From there I went to San bernadino, again, all through pass roads.. Fabulous scenery and amazing riding roads... From there to Davos, and then the long road out of Davos to Stelvio.. the first 15 miles out of Davos is the key...
If you take the long road out of Davos via St Moritz etc, you will pass through some more amazing passes along the way... Stelvio itself, I wouldnt say its a riding road at all, but 30 odd hair pins up the south side and 47 down the north side makes for a fairly interesting experience.. I can recommend camping at the end of the North side in Trafoi just for the view.
I then headed to Como but again the long way round, via Belzano (mate had a problem with his Buell and had to go to HD dealer), it took twice as long, but it leads you through the Dolomites and the Tonale Pass... again areas I would recommend as not to be missed.. all in all from Basel to Tonale, took approx 3 days, but that was riding slowly and setting off at 10am stopping for about 4.30 ish to camp B&B..
Add in some long lunch breaks etc, and you could comfatably do the whole lot in 1-2 days...
Advice - Self catering in SZ as its expensive.. was glad to arrive in Italy for the cheap food and

...
But dont miss out Switzerland, it offers a lot more than a diversion on the map!
Just my pennies worth.. heres some videos I made after the trip... cheesy I know

... enjoy your holiday which ever route you take!
YouTube - Tour 2010 Preview
YouTube - Tour 2010 San Bernadino Davos
YouTube - Tour 2010 Davos to Stelvio
YouTube - Tour 2010 Stelvio PassNew version
YouTube - Tour 2010 Setting up the camp! (ok a little off topic, but it was the trafoi campsite).
Shamelss self promotion, I apologise!