Day train trip from Brussel vs. staying in different cities?

I think you’ve answered your own question. With such a long time here, I would definitely switch bases. Ghent and Bruges are doable as a day trip from Brussels, but Amsterdam is not. You have to take into account that day light is short at that time of year. Besides, Amsterdam deserves much more time than just 1 rushed day.

On our trip to Belgium we stayed in Antwerp, Bruges and Gent with a daytrip to Brussels. It can be more tiring to do several daytrips versus changing hotels one or two times and being able to soak up the local atmosphere. Amsterdam does deserve more than a day but if it is a priority, a day is better than nothing and may help you to decide about returning in the future. We loved Antwerp and it is convenient to all of your choices so you could divide your week between it and a second location.

Brussels is not as interesting a place to stay as Ghent, or better, Antwerp. That also reduces travel time. Your plan to stay in one hotel is absolutely fine-check museum closing days of the week, of course. The only exception to this decision is the percentage of travelers who consider Bruges to be the most beautiful, romantic place in all of Europe. While it is very nice, I don't find an extra two hours each day before and after the CRUSH of day-trippers come to be worth being stuck there. Antwerp has so much more to do, and is cheaper. (Ghent is probably even cheaper than Antwerp, but I haven't slept there.)

You are mistaken in believing that Amsterdam is next to, or a day trip, from ANYWHERE in Belgium. Amsterdam (unlike Brussels), is a major city of the world, good for five days easily on first visit. (I've been there at least four times, counting two business trips.) This is not like driving from one mall to another for shopping. You don't visit Chicago from Cleveland. (I used to live in Cleveland.)

I understand the convenience of staying in one place instead of switching hotels, but trying to day trip anywhere in The Netherlands from Brussels is a bit of a stretch. Keep in mind that many hotels will hold your luggage even if it's too early to check in. Also, many train stations have secure luggage lockers. I recently used them in Haarlem and it worked out perfectly. I used them in Ghent on a visit to Belgium a few years back. Taking advantage of these can be better than using one place as a base and taking long trips back and forth. That said, using Brussels as a base to visit other cities in Belgium is totally fine.

You don't visit Chicago from Cleveland. (I used to live in Cleveland.)

The difference being that Chicago to Cleveland is 346 miles, Brussels to Amsterdam is 131 miles. The first has little or no public transport (except air) and takes over 5 hours of driving. The latter has frequent public transport and takes just under 2 hours, on which you can sit back and relax.

Different as chalk and cheese.

While Amsterdam may be better as an overnight, with an early start and a late return it is totally viable as a taster day trip if this is a first visit. You can get 10 hours or more there. You can always come back to Amsterdam or any of the other cities for a longer trip

As is often said on this forum you lose a lot of time with moving hotels every few days.

I am one here who does far longer day trips as a matter of normal routine as do many Brits. Personally that is an itinerary I wouldn't even blink at- totally do-able to me.

Day trips from Brussel to Ghent, Antwerpen or Brugge are definitely easily doable. Amsterdam is not. You can get there, but it will take a long time and then you’ll need to go straight back. Antwerpen is an hour or more from Brussel, and Amsterdam is several hours from Antwerpen.

You might consider starting in Amsterdam for a few days, going to Brussel as a base for your Belgian cities (although Antwerpen or Gent are more centrally located) and then continuing to Paris.

A longish daytrip makes a lot more sense when the base you're traveling from is your home and thus not costing you anything. It's different if you're paying Brussels hotel rates and spending a good chunk of your day in transit to Amsterdam. I live in Washington DC. Door-to-door it would probably take me about 2 hours to get to what I want to see in Baltimore (there's rail service). I've done that once and might well do it again. There's no way I'd daytrip to Amsterdam from a hotel in another city requiring 2 hours on the train each way. YMMV, of course.

Edited to add: I should note that I have occasionally made side trips to places 2 hours or so away, but the targets were little towns with not enough to keep me occupied for more than a few hours.

One person's "Taster Trip" is another one's "Tick the Boxes". I love daytrips, but two hours is my limit. I would check out of the Belgian hotel and stay the chosen number of days in Amsterdam, whether or not you choose to go to Paris from Amsterdam. Paris is closer from either Brussels or Antwerp.

I would also mention that Amsterdam is a place that has a number of high-priority unreserved local train daytrips, just as the proposed area of Belgium does. That's an argument to allocate even more time to Amsterdam.

I will mention that buying train tickets can be troublesome for Americans in Belgium. Bring a few credit cards to make sure you have one that will work in a ticket machine, and avoid long lines for human agents. Success HAS been reported here by Americans.

I agree that an Art History person might need more than one day in Brussels. But Antwerp has equally important art (in multiple museums), if maybe a smaller quantity than Brussels. I have made three daytrips to Brussels from Antwerp, and only slept in Brussels for a long-ago business trip that had to be there. I like Brussels fine, but the unified Ancient/Modern art museum aside, it is not a major city of the world. Antwerp is incredibly popular with European travelers.

I would suggest if the radius is under 2.5 hrs. each way, then stay in Brussels. I would . Staying in different hotels in and of itself is not all that unpleasant but it's the distance from the train station to the hotel, ie how convenient is that.

For me it has to be within walking distance. Therefore, most of my hotels are near the train station. Not interested in taking public transport from the train station, much less ride sharing. That is not an option.

On losing a few hours each day, that depends if you can arrive prior to noon.

I think there are pros and cons to basing in one place, as you’re seeing here.

Having been to Brussels, Amsterdam, Paris (and other towns mentioned in this thread) rather than question whether basing in one place is good, I would question your days distribution.

I like Paris and Amsterdam infinitely more than Brussels. It’s not even close! Brussels has a few nice things to see but Paris and Amsterdam are both superior in just about every way. Perhaps there is a reason you are staying in Brussels like family or business but if not, I would give more time to Paris or Amsterdam. But, like you’re seeing, travelers have different preferences and ideas about what to explore and how to do it.

Enjoy!