One of the first mishnayos introduces an incident in which Rabban Gamliel's sons return home from a night of drinking past midnight (that's not hard to imagine - a lot of times that people return home past midnight involve a night of drinking, even to this day). We don't know anything else about the drinking house, aside from it was where drinking took place: we don't know if it's someone's house at which drinking took place, if it was a public house (such as a bar) where drinking was meant to take place in a commercial sense, or some other location.
In this mishnah, we are informed that pre-cessation of the Sanhedrin, it was common for people to engage in singing during their drinking sessions at these drinking houses, but, owing to an unspecified cause, people no longer engaged in singing while at these drinking houses.
It is unclear whether singing was more universally dropped from the these drinking houses or only mostly - maybe people occasionally broke out in song at these drinking houses.
It is also unclear whether or not people had musical instrumentation typically accompanying their singing while at these drinking houses.
One thing that does seem clear from the language deployed in this mishnah is that song seemed to have ceased from these drinking houses due to some sort of national sadness, rather than any sort of [rabbinic] decree.
One comment to make is that the mishnah from Ketubot does not allow a husband to forbid his wife from going to either a house of mourning or a drinking house, since this is locking her in. The Talmud comments that this is obviously unfair to her (bKetubot 71b-72a), seemingly since people need to be able to go to either drinking houses or houses of mourning, as part of normal living.
These three mishnayos (mTerumot 11:10, mEruvin 8:1, and mKetubot 7:5) all pair the drinking house (בית המשתה) with the mourning house (בית האבל), which seemingly draws from Ecclesiastes/קהלת 7:2, one of the three times that the phrase בית המשתה is found in the Bible/תנ"ך (the other two of which are Jer. 16:8 and Est. 7:8).
It seems that these three mishnayos all draw upon this language. One thing that the mishnaic authors could be reflecting about the drinking house and the house of mourning is that just as the house of mourning is at someone's house and there just happens to be mourning taking place at certain times and not that it always exists as a someone's place of mourning, so, too, a drinking house is merely someone's house where a drinking session is taking place, rather than an enduring building for coming together to drink. Nevertheless, it is still merely speculation, so I'm not 100% convinced.
We could also check out what the Tosefta has to say about the drinking house....
From this text, it would seem that the house of drinking was not necessarily like that of a bar, per se, in which wine or beer might be sold to customers, but perhaps more like that of a house/building in which people bring their own drinks (most likely to share) from which they could consume their wine(/beer).
While we had seen mSotah describing singing at houses of drinking, this text describes bringing wailing pipes to a house of drinking (and house of rejoicing), so there may be other instruments that may have been brought to houses of drinking.
The phrase "house of celebration" (בית השמחה) does not appear at all in the Mishnah and the only two times it appears in the Tosefta are here in tBeitsah and tMoed Katan.
In these two texts (tBeitsah & tSanhedrin), it would seem that it was not a common occurrence to bring children to drinking houses, but that they may be brought there, as long as they are somehow not part of the main action going on in the drinking house.
This text is very similar to mKetubot 7:5, except that it posits a different reason for the divorce, although this reasoning seems a bit weaker than that offered in the Mishnah.
Having knowledge of Ecclesiastes 7:2, it is quite unsurprising that Rabbi Yishma'el would give precedence to a house of mourning than going to a house of drinking. However, it is quite fascinating that the text suggests one give precedence to attending a house of drinking over that of a house of mourning!
It is also quite interesting that all of the mentions of the house of drinking in the Tosefta pair up with a house of mourning, with the lone exception of tSanhedrin 7:5, perhaps because it is exceptional, in that we would not be surprised to see children at a house of mourning, but we would be surprised to see them at a drinking house.
You may also be curious: how is the term משתה (drinking) used in these bodies of literature? The term משתה appears twice in the Mishnah