If people are drinking wine together and then resolve that they’re not going to drink any more wine, they say, “Okay, we’re not bringing any more.” Then they change their minds and decide to bring more wine to the table, and that wine is a better choice of wine. They do not recite the Beracha (blessing) of HaTov HaMetiv (the good and beneficent) because they had resolved that they were not going to drink any more. This is what’s called Hesech Hada’at. They took their mind off of the wine previously. If they bring more wine to the table, they have to make the Beracha of Boreh Peri HaGefen (Creator of the fruit of the vine) instead of the Beracha of HaTov HaMetiv.
For this same reason, if you brought a special wine to the table to make the Birkat Hamazon (Grace after Meals) al ha-kos (over the cup), and they had been drinking a different wine during the meal, they don’t say HaTov HaMetiv over the cup of Birkat Hamazon. Since they recited Birkat Hamazon, they ended the Beracha series from before, and they would have to make Boreh Peri HaGefen on that cup. Therefore, they would not make HaTov HaMetiv.
Even though the Beracha of HaTov HaMetiv is considered to be a festive, joyous Beracha, one still makes HaTov HaMetiv even in the house of a mourner. So if they bring multiple wines and they’re drinking, HaTov HaMetiv would still be recited in a Beit Avel (mourner’s house), especially during the Shiva (seven-day mourning period), if it was Shabbat. However, the Poskim (halachic authorities) do write that during the Bein HaMetzarim, during the three weeks period, when we typically refrain from saying Shehecheyanu (Who has kept us alive) and minimize our joy and happiness, it’s appropriate for a person to avoid the circumstances that would require them to say the Beracha of HaTov HaMetiv, unless it was on Shabbat.