Don't know De Republiek Cecilia.
Our vibrant night after dinner was in café Brugs Beertje where we've mixed with Brits who were beer tasting (mixing all different kinds of strong beer, ouch) and it was fun. It's an excellent beery bar, not open very late though.
And yes we have done a boat tour as well :)
I agree you have to set your mind on it. Have never done a boat tour yet in Amsterdam.

For vibrant nightlife you better go elsewhere :)

Ha ha I know what you are saying about crazily touristy. Sometimes I "claim back" the overrun center of my city Amsterdam and sit on nice terraces surrounded by tourists (and having to correct the waiters that I do speak Dutch), and sometimes even do a super touristy boat ride. It can be fun sometimes. But you have to set your mind to the intense crowds.

I can't remember which day of the week I was in Bruges that time, but I had good cocktails at a vibrant bar called De Republiek. It had a nice large courtyard so we sat in open air.

Because of the following i suspect the OP intends staying overnight in Bruges.

What are the travel options from Amsterdam to Brugge? So far, I got to know about Flix bus- did anyone use it? How was your experience? Does it take 6 hours? Any breaks/stops along the way?

Now i am not going to promote Bruges (over anywhere else), i almost never do that. But i do think that staying overnight there isn't such a bad idea at all. In fact it would be a great way to escape the crowds, if one desires to see it.

As a Belgian of course i have time enough in this country, and a couple of years ago i had to attend a fair in Bruges on a sunday, it was late spring so the days were long. A few days before i convinced Mr A to do something crazily touristy for once and to stay overnight there until monday. Even though the drive back home wouldn't take more than an hour and 15 minutes, i had never stayed in Bruges by night and wanted to try it. To my surprise it was easy to find a last minute hotel room. By 6pm most of the crowds had left and i fact it was very enjoyable, even quiet. For vibrant nightlife you better go elsewhere :)

Hi have you thought about hiring a camper. We have done it 8 times and there are plenty of campsites along the rivers. You can hire from mcrent Amsterdam which is actually in Almere.

I did Ghent as a daytrip once, but that was by car. We left super early in the morning to beat any traffic jams, and swapped drivers halfway. About 2.5 - 3 hours one-way as far as I recall. And having the car also allowed us to stay quite late until 10pm and then drive back well after traffic jams.

If you go by bus or train, the latest one back is a lot earlier than that and you have much less hours in the actual town you're trying to visit.

For us this was kind of a "joke" trip with a very specific goal, a vintage wallpaper shop in Ghent.
And we were still utterly exhausted having done it as a daytrip, even though we had spend about 13 leisurely hours in town. I would never do "just another daytrip" to a place that takes that much travel time if I did't have a very specific goal or reason. I think my personal rule of thumb is 1.5 hours one-way is about as far as I will go for a daytrip; if it takes more travel time then I want to stay there for a night.

Perhaps my mind is blurry but I don't recall what should make Bruges that much more special than any of the medieval towns in the Netherlands which I just mentioned, and which are much closer to Amsterdam. Except the fact that they are not as well known to the general public. (To me, that makes them more interesting.)

And some more info: https://www.seat61.com/trains-and-routes/amsterdam-to-bruges-by-train.htm

And Amsterdam - Paris, about the same travel time... https://www.seat61.com/international-trains/trains-from-Amsterdam.htm#Amsterdam-Paris

I agree with Artemis' suggestion for the normal intercity to Antwerp and then an onward train. You can buy those tickets (fixed price) on the day of traveling. You could even get off the train in say - Rotterdam, explore there for a few hours, and get back on a later intercity to continue your journey. Your intercity ticket is valid all day (as opposed to Thalys tickets which tend to be for one specific time and train, unless you pay EVEN more for a flexible ticket).

Indeed, traffic jams can be terrible so if you go by bus you may lose lot more hours.

And no, flying is not a valid option at all unless you can afford a private helicopter.

But.... about the same travel time would get you to Paris (3:20 one-way). So why go through all the hassle for Bruges... a town that is not all that much more special than Haarlem (20 minutes from Amsterdam), Utrecht (25 min), Leiden (30 min), 's-Hertogenbosch (1 hour from Amsterdam), or medieval hansa town Deventer (just over 1 hour)... in my humble opinion.

I don't think Bruges is 'daytrip material'. If you are dead set on going there, then go for 2 days and combine it with lovely Ghent. 30 minutes by train from Bruges. And stay overnight in either of the two.
Ghent has a medieval castle in the center, gabled houses and canals, loads of quirky shops, good restaurants and cafes, a student vibe, and is not as overrun by tourists as Bruges is.

Just a little tip: If you are going "down" the river Rhine from Amsterdam you are in the Nordsee. Go the other way, the Rhine up to Köln. And has your stop in Miltenberg a special reason?