Base City for N Europe Layover
 

Before returning to the US after a trip to Spain in July, would like to get a taste of Northern Europe.
Criteria:
-One base location for 4 nights. Day trips by rail.
-Easy access to international airport (fly in from Barcelona, out to NYC)
-Things high on list to see: castles/medieval town, architecture over museums, WW2 sites?
Amsterdam, Frankfort, Munich? (We are Dutch heritage, so biased towards seeing some of Neth.)
Any other suggestions?

If you are of Dutch heritage and haven't been in to Amsterdam, it would be an ideal location for 4 nights. I'd plan just one day trip (at most) as you only have three days, and could easily use that time in Amsterdam. Do a bit of reading about Amsterdam and find what you most want to see/do/experience while you are there.

Kinda what I was thinking.
Arrival day + 1 day in Amsterdam
Day trip to Bruges for the Medieval taste
-Another good day trip?

I know it's not much time, but this is secondary to our original trip (we'll be back to see it in detail later)

I find a day trip to Bruges a little too much. It will be about 6 hours in the trains ?
So if you want another day trip make it to Gent. Beautiful town too and they have a castle.

I would stick with the Netherlands with only four days. Do you know here your family come from? Perhaps you could visit that area. Otherwise stick with Amsterdam and chill. Go to Haarlem or Delft or somewhere similar if you want a day out. Muiderslot if you want a castle.

If you are planning to return save Bruges, and Gent for that trip. In July Bruges will be heaving any way and really hard to appreciate.

It's not four days, but four nights - just three days. I'd skip Bruges, there are plenty of picturesque towns in the Netherlands that won't be crammed with tourists. And I found Bruges a bit too "Disney" for my tastes.

And consider staying outside Amsterdam. Haarlem, Leiden and Utrecht are all within 30 mins of Schiphol airport with excellent rail connections, and give you much more a Dutch experience than Amsterdam.

Thanks.
Keep the suggestions coming.
I don't mind opposing views.
Will be travelling with 3 kids in their late teens.
Ann Frank house is a must, but not much else they've mentioned. Bruges is my wife's request (3 hours each way by rail?)

Ancestors are Friesland, but not imperative that we see it.
Classic Holland (windmills, etc) would be more of interest.
Lodging outside of Amsterdam would be fine.

Is Muiderslot a classic castle?

I'd be fine with leaving the castles for a later trip to Germany if we can make this visit more efficient.

The Netherlands is beautiful and would be a lovely contrast to Spain.

Harlem, Delft, Leiden, Utrecht are all interesting and beautiful, most within 30 minutes to less than an hour from Amsterdam. I have been to all of them and Bruges and Ghent. With so many places to see close by that are equal to Bruges in beauty - canals, flowers, bridges, architecture, food, art, etc. it would be, IMHO, a big waste of time to spend 6 hours going back and forth for a few hours in Bruges or even Ghent. Spend more time seeing and less time on a train. Google some images of Delft and Leiden. I promise you, what you will see in The Netherlands will as good, if not better, than Bruges.

The suggestion to stay in Haarlem is good. Visit Amsterdam (30 minute trip) one day and Delft (about 40 minute trip) another day. Get to Leiden also, if you can.

There are several books about Tulipmania, but one of my favorites is Tulip Fever by Deborah Moggach. Your wife might enjoy it. Not great literature, but at least entertaining and interesting and a good look at how The Netherlands developed such an attachment to growing bulbs.

Ancestors are Friesland, but not imperative that we see it.

Can I suggest a visit to the Zuiderzee Museum in Enkhuizen (a beautiful 17th century city frozen in time)?

https://www.youtube.com/watch?v=Y9IJDGzBgCM