Fodor's Travel Talk Forums - Need ideas for our next Europe adventure

Husband and I are heading to Europe in early September. Originally we were going to do London and Provence, but since we were just in Provence this past May we've decided to forego it for right now and visit somewhere new instead.

So these are my thoughts right now. As we're in the very beginning stages of planning, everything is very much up in the air. The only two parameters are a) London is a definite and b) we are going to be working with frequent flyer miles, using a Oneworld ticket so we can build in several destinations into our business class ticket so that will save on inter-country travel. Oh, and total trip duration will be between 12-14 days.

1) London is a must-do for this trip. DH's ex-boss lives in London and has invited us to stay there, but he's only contracted to work in London for one more year so we have to get there soon. I know we could probably spend a whole week in London, but we don't want to overstay our welcome. So we were thinking, fly in on a Friday morning, spend Fri, Sat, Sun with boss and his family, and then on Monday catch a flight to our next destination... Salzburg.

2) Due to several trip reports I've read about Austria and my obsession with the movie Sound of Music, I would like to visit Salzburg. How many nights would be sufficient for Salzburg? (also we may do a day somewhere in the Salzkammergut region, but I have not yet read enough about this area to figure out what all there is to see/do here)

3) Thinking of visiting Germany from there... maybe taking a train just to over the border and then renting a car. Where does the "romantic road" officially start? Does this take you all the way to Munich? Obviously I need to do some research.

I was thinking of maybe 4-5 days to explore this region of Germany.

4) Somehow I'd like to get to Amsterdam too, but I don't want to have to drive all the way across Germany, so where would be a good point to drop off the rental car and get a good train connection to Ams? (hopefully a direct train) I would be fine with 2-3 days in Amsterdam since I've been there before but I want to show my hubby around.

5) Fly out of Amsterdam.

Another option is to skip Amsterdam this trip and fly home either from Frankfurt or Munich. What do you think?

Basically I am open to any and all suggestions... the only absolute is London on this trip but everything else is workable. We were even considering just an all UK trip too. So if you have any itinerary ideas for me, they'd be most welcome.