Anything around Valkenburg is great. Or, there is a vacation park on the Vaalse Berg, which might be more fun for your daughter.

Riding the hills in Zuid-Limburg is awesome, but not sure if it will prepare you for La Marmotte. But then again, not much will ;)

There are a lot of "famous" hills on the Dutch side you can look up, like
-Cauberg
-Kuetenberg
-Vaalse Berg
-Gulpener Berg
-Camerig
-Eyserosserweg

and of course many more. And that's only the Dutch side, you can always make a detour and explore the hills in Belgium. What I like to do I to just ride, and go pick any road that goes up.

The Amstel gold race routes are well signposted and take in most of the hills mentioned.
If you stay in Valkenburg thats right by the start of the routes and its a pretty nice town. Maastricht is not too far away and there's plenty of culture there.
Trains from Den Haag take a couple of hours with just one change in Rotterdam IIRC

The most entertaining thing to do is listen to the locals' accent.

---

NO

For road cycling i'd also recomend following the Amstel Gold signs if you don't know the area well. You could also follow the route of the "Mergel heuvelland tweedaagse".
You could also consider taking your MTB/XC bike, there are a bunch of marked XC routes that can be linked together.

https://www.mtbroutes.nl/home


I don't know how old your kids are but you could visit the limestone caves in Valkenburg. You can explore them on foot or by bike.

https://www.vvvzuidlimburg.nl/...EAAYASAAEgKzCvD_BwE#

You can also go to the "3-landen punt" where the borders of Netherlands, Belgium and Germany come together. There are very high towers you can climb with a great view of the area and there's also a large playground.

Take a look at the Amstel Gold Race route, at least 15 good climbs in that area. If you can swing it, go for the Amstel Gold Fondo in mid-April, it was great and rides all the hills.

I'd make it a few weekends around Maastricht (anywhere is the area is good) and a few weekends in the Ardennen (around La Roche). Not really a preperation for the Marmotte, but if you can't train in the mountains, this is your best option.

As for routes, just go on to strava and search for rides with high altitude meters / hoogtemeters in the area. You will find plenty of them.

If you're training for the Marmotte I'd recommend something like this:
https://www.gpsies.com/...eId=vukduwzzxvvnmqzg

The climbs are slighly longer and not so steep (between 6-10%). Sippenaeken is nearby Valkenburg. Maastricht is a great little town for your wife and daughter to visit.

Good luck riding the Marmotte!

I would start my ride out of Valkenburg, and to be more specific the Amstel Gold Race Experience Center (http://www.amstelgoldracexp.nl/agecheck.aspx). Website is in dutch. Here you can start your day with a cup of coffee and top of your bottles. On the website they have the three loops as gpx-file. All the routes are permanently laid out with signs.

As for things to do, it depends on the age of your daughter. Maastricht is a nice town, as is Aachen (in Germany, just across the border). There's a giant spa in Valkenburg. Valkenburg itself is quite a nice village. For the smaller kids there's an amusement parc in Valkenburg.