Hello Dave,
I have been to that store in Amsterdam. It is conveniently located. You may find that model of few years ago that you didn't buy and regret there (I found my Mä 37021 BR 53 Borsig w/condenser tender there), but be aware that their prices are on the high side.
Prices are much more competitive in Germany.
I agree with Zora la rousse about Muller department store for buying the not fancy items

.
I guess that you will be travelling by train, the only civilized way

, and will get into Lower Saxony into the Rhur valley and then to Rhein river.
Depending of where your train connection is you may go by Osnabrück (Osnabroeck). There are 4 train stores. Plus, a worth visit to Felix Nussbaum (painter) Museum and writer Erich Maria Remarque, "All Quiet on the Western Front", small museum near the university. They are two of most know people born there that unfortunately were killed by that WWII government.
You may check this store for nice variety and presentation models 1 to Z :
J.B.Modellbahn-Service
http://www.jbmodellbahnservice.dePeter Schwenderling is my salesperson over there.
If you make there, is worth a visit to the city Müster (30 min south) for the history of 30 years war. Sorry, no train store of note.[:(]
In the Rhur valley:
Dortmund:
Der Lokschuppen Manfred Berlinski (2,6 km from main station by street car)
Märkische Str. 227
44141 Dortmund
Essen:
Müller Ltd. & Co. KG Deptartment store(0,4 km)
Limbeckerstr. 59-65
45127 Essen
Modellbahn-Ecke Inh. Ursula Aschmann (2,9 km)
Kölner Str. 48-50
45145 Essen
Dusseldorf:
Nothing that I remember.
Wuppertal: Land of
Schwebebahn
suspended monorail
MATSCHKE Modellbahn - [:p] My 2nd favority Marklin Store
42281 Wuppertal -
Schützenstraße 90
Cologne:
Köln HaupbahnhofMain train station,
Kölner Dom cathedral, Ludwig Art Museum and
Römisch-Germanisches Museum Romano-Germanic Museum. These are not to be missed attractions.

There are some stores, but too much to see and no time for toy train shopping [|)].
My favorite store in whole Germany:
Eisenbahn-Treffpunkt SCHWEICKHARDT GmbH

Biegelwiesenstrasse 31, D-71334 Waiblingen-Beinstein,
Telefon ++49 7151 93 79 31
http://www.modelleisenbahn.com/index_e.phpmy salesperson:Jens Schubert

This store is near the size of Safeway! Best prices too.
Waiblingen is about 11 miles from Stuttgart and it can be reached by local train and taxi.
REMEMBER [:0] :Stores are closed on Sundays and open only half day on Saturdays- Plan ahead![}:)]
Enjoy your trip.
Ed
p.s. I copied this text from my notes that I compiled to myself for my friends and I went I go over there.
