Yeh - wot she said (Minnie). Stunning route. Don't listen to Matt (On this occasion!) I think he's got too used to flat roads!!
Switzerland is wonderful biking country, but do stick to the limits unless you are very rich. (Actually, you need to be pretty rich to buy anything there). Beware vicious unmarked speed humps in absurd places in villages. ALSO, GPS with speed trap warning capability are illegal, and can be confiscated.
Around the large cities, especially in the low country, traffic can be very slow and the roads very dull.
Allow MUCH more time for your journey than it looks like on the map, unless you use the motorways. For which you need a "Vignette". I think you have to shell out for 12 months, which makes it an expensive proposition, especially as there's no discount for bikes. I've never done it myself though - can't see the point of going to the Alps and driving on an M25 clone.
If you go via Austria - and why would you not? - note that many passes charge a toll, which means you have to pay to get into the country! But it's brilliant when you get there. (Google "Grossglockner")
Italian traffic is totally insane. I hate it. My mate Graham thinks it's wild fun! Expect to be overtaken by Vespas and Fiat 500's going flat out around blind bends. There is a speed limit on Italian motorways, but if you stick to it, you'll be forced off the road. "Stopping Distance" in Italy is about 4" from your rear wheel. (Must have different Physics there). I had my foot driven over in an autostrada traffic jam by a Mercedes driver who's virility would have evaporated if he didn't get half a metre further forward. I wasn't filtering; he was! (well, trying to).
I could go on, but I should be working.
Have fun!!