8 days in Amsterdam---help with day trip(s)!

Don't. You could reasonably get to and return from Brussels or Paris in a day. But why? You won't have enough Hume to really see them. Visit one of the dozen or so towns in The Netherlands within an hour and a half from Amsterdam by train. We visited Haarlem, Delft, and Alkmaar, and barely scratched the surface of the possibilities of easier and cheaper day trips. Visit Paris when you have time to stay in Paris a few days.

On the other hand, one does not need as much David Hume to enjoy Paris as one once did.

Ain't spell check grand? I have this picture of turning ones morals over at the French border. . . And it's too funny to consider correcting my first post.

And see the RS book on the Netherlands for some other suggested day trips. There's lots to do in that area.

Rick's Netherlands book has a ton of day trips, complete with goof-proof directions for getting there by mass transit. These range from cities to small villages to rural areas. And none require advance planning, so you can just decide on the day what you feel like doing.

If you really want to do a day trip to Brussels, that's only 2 hours each way by direct Thalys train. The catch is that the Thalys is €29 each way if booked in advance as a non-refundable ticket, and up to €99 each way at the last minute. You can also go by slower local trains requiring a change; these can be as low as €19 and as high as €45.80 each way, but they take 2:45 to 3:17 each way - too long a day for me.

Then there's the fact that Brussels is not my favorite place (understatement alert). And I'm certainly not the only one who feels that way. If there's something specific you want to see or do there, like one of the museums or the Art Nouveau tour with ARAU, a day there can work. Otherwise, it's not worth the time, expense, and hassle. ARAU: http://www.arau.org/en

If you insist on a Belgian day trip destination, Antwerp is very worthwhile and closer than Brussels. But I'd focus on Dutch daytrips instead.

Paris, Luxembourg, and (most definitely) Hamburg are too far for comfortable day trips.

In addition to the possibilities mentioned by #1, there is Hoorn (a historical former port town), Utrecht (lively Oudegracht; peace and quiet around the Dom), Dordrecht (oldest city in Holland, as the western part of the country is called), Kinderdijk (the world-famous windmill complex; easily combined with Dordrecht, from where you've got a regular ferry connection).
It's all within easy reach of Amsterdam by frequent trains. Check at the website of the Dutch railways.

Even though Rick's guide doesn't mention them, I always enjoy the short trip (1:15 minutes by train) from Amsterdam out to the National Park with the Van Gogh collection, as well as the eastern cities of Nijmegen and Arnhem. Since I am very interested in WWII, these cities, with their great museums and battle sites are "must sees" places for me.

I second the recommendation for a visit to the Kröller-Muller museum and sculpture garden in the Hoge Veluwe national park, near Arnhem. Despite the name, it is accessible easily by public transportation.

Not sure if it qualifies as a "day trip", but a nice day out would be to rent bikes near the central train station, cross the river on the little pedestrian and bicycle ferry ( it's free), and spend the day cycling around Waterland - very pretty, rural, little if any car traffic - mostly dedicated cycling paths - and flat. If you're especially ambitious you could make a circuit up to the the villages of Marken and Monickendam for lunch and return later in the afternoon. It's a very Dutch thing to do - and one of our favorite memories during our visits to Amsterdam.