Amsterdam - then what?
 

My husband and I plan to spend 4 nights in Amsterdam. We have 4 nights free after that before we need to be in Hagen, Germany (near Dusseldorf).

Any suggestions on where we should go?

We are both 50's.

I thought that a guided bus tour might be interesting and that we could cover a lot of ground with a bus tour.

Paris?

Paris may be a bit out of your way if you need to go to Dusseldorf later , a bus tour of Holland and Belgium may be an idea.

I would rent a car and go the slow way through Belgium - not on expressways, but village to village with a keen eye out for the unusual, quaint, like a snail farm here, a glassblowing artisan workshopt there, country pubs galore with a lot of character, and on and on. Carefree - stop and ask for a room in guest houses in tiny towns whenever/wherever, experience the real Belgium that way. Much fun!

Brugges and/or Belgium?
Can be done by tour, or easily enough by train on your own.

We've stayed in Amsterdam for a week each several times. There are a couple dozen interesting towns to go to easily by train for day trips. Delft, Rotterdam, The Hague, Haarlam, Enkhuisan, Hoorn, Gouda, just to name a few. I'd add a few days to Amsterdam possibly and just stay there doing day trips. Coming back to Amsterdam each evening is wonderful. We also did a day going to Texel Island and bicycling for the day -- splendid.

My next stop if I did one would be Brugge for a couple nights.

Visit lovely cities like Arnhem, drive along river Rhine etc.

Certainly try to get Harlam in then go down to Zeeland by train and visit the little towns out on the islands there (middlebourg etc) all by train or car) idle down to Luxemburg (the city is worth a visit) and then back up the Moselle into Germany. Lots of castles, wine, museums etc