How on earth did I miss this topic?! Currently living in Belgium and have lived in the Netherlands for 4 years, shoot me a message with any specific questions you might have, I'll be very happy to help!
Some tips for The Netherlands:
- As mentioned above, Keukenhof to see the tulips. It's very touristy but still really cute!
- the Wadden Islands. It's a quick ferry ride away from the mainland, the beaches are beautiful and calm and there's lots of nature. If I'm not mistaken most ferries leave from Harlingen.
- Hoge Veluwe NP would be absolutely beautiful for a bike trip.
- Be prepared if you're gonna ride a bike in a major city. If not, mentally prepare yourself for the insane amount of bikes you'll encounter.
- Amsterdam seems to be choice n°1 for tourists and while I won't tell you to skip it, there's nicer, cleaner cities to visit with a more authentic feel to it. Personally I like Utrecht, Zwolle and Maastricht more to name a few. Rotterdam has a bit of a Berlin feeling to me, if that's your scene.
- I'm biased because I lived there, but I like the Southern part of the Netherlands the most. Valkenburg is a really cool small town with beautiful surroundings and Vaals is worth a visit for the maze and because it's the point where the Dutch, Belgian and German border come together.
- If you're heading down to South-Limburg and want to do something unique: go to Snowworld! It's Europe's biggest indoor skiing centre, has a slope length of 520m and a really good funpark. You can rent everything you need on-site.
Belgium:
- If coming from Maastricht/Valkenburg/Vaals, you can head to the Ardennes region via Liege. Liege is probably the most underrated city in the whole of Belgium. Try to get there on Sunday, you'll find the biggest outdoor market of Belgium (called La Batte) on the river banks! Get your calves burning on the Montagne de Bueren and have a drink in the Le Carré district at night.
- The Ardennes region is by far the most beautiful part of Belgium with rivers, hills, forests etc. Some places are more well-known than others. I'm not gonna write all of them down, let me know if you think about visiting that area and I can give you some addresses.
- Kempen NP is similar to Hoge Veluwe NP in the Netherlands, but just across the Belgian border near Maastricht. there's dunes, meadows, some forests,...
- Antwerp: the hipster city of Belgium and fashion capital. Make sure to keep an eye on your budget if you're going shopping, it's soooo easy to spend fortunes there!
- Brussels: rougher around the edges than Antwerp but a must-visit for anyone I think. It's the capital of Europe after all :-)
- Not a popular opinion but I really dislike Bruges. To me it feels like a bunch of old bricks and canals used to lure tourists, feels fake even though the buildings are real. Ghent has the same type of architecture but people also actually live there and it shows.
- Chocolate and beer tasting is a must of course. I like the Hoegaarden brewery the most but there's tons of places to visit, I'd say check for one on your itinerary. My favorite brands of chocolate are Côte d'Or (supermarket), Leonidas (good budget-friendly choice) or Galler (try their spreads, the hazelnut one is delicious!!!). Pierre Marcolini is the current hotshot if you want some designer chocolates.
- Don't buy beer in tourist shops!!! Apart from a few specialty beers, most can be found in bigger supermarkets around town, even the niche beers! Try a decent-sized Delhaize or Carrefour, you'll find plenty of special local beers to try without being ripped off.
- If you like art, you'll hit the jackpot in Belgium. Most of the museums worth visiting are in Antwerp and Brussels. My personal favorite is the Magritte Museum.
I could go on like that for a while but it might be good to know if you already have an itinerary in mind? I can give you some tips for places to eat and drink in Antwerp/Brussels/Leuven if you're visiting either of those. Last but not least: while we don't have real mountains, Belgium isn't as flat as the Netherlands. As a matter of fact, not even the Netherlands is as flat as they make it out to be if you go to the South. I don't know if flatness plays a factor in your wish to do a biking trip in the Netherlands/Belgium, but if it is that's something to keep in mind.