This was my husband and my trip in 2010...learn from our mistake...
arrive London early morn, train to Paris 3 nights, Strasbourg 1 night, Augsburg 1 night, Munich 1 night, Salzburg 2 nights (and overnight train to Venice), Venice arrive early morn from train then 3 nights, Milan 2 nights, off to Switzerland with 3 1 night stays (Spiez, Bern, Zurich) then fly back to London 2 nights, visit sister in Portsmouth 2 nights, back to London for a night and home...
...so we had 21 nights...and here is what happened when we were looking at our photos - I hit Munich - hubby couldn't even remember being there - by the time we arrived in Munich from Augsburg (due to a lovely couchsurfer we stayed with, we left Augsburg way later then we planned), it was after supper so we went right to the hotel, had til about 4 pm the next day before heading to Salzburg. Strasbourg was lovely, but by the time we went from Paris to Arras, back to Paris and on to Strasbourg, it was very late when we arrived - we had about 4 hours the next morning before we had to go to Augsburg...you get the picture. Yes, we 'saw' lots of stuff, but we didn't really 'see' anything. I used to pooh pooh those who said you have to take in account changing hotels - it can take a few hours ++ out of the day to change, get settled, figure out what to do (unless you have a car - much easier then having to find your way from the train stn using public transport).
I planned the vacation that way because hubby wanted to see 'everything', but even he admits (now) it was foolish to try to pack so much in...tho we still try to pack to much in, but try to stay at least 2 (or better, 3) nights at each stop...the only thing it did was make me want to return to Strasbourg and Switzerland and...