If people drank wine together, and then a different kind of wine was brought to the table, they recite the Beracha of "Ha’tov Ve’ha’metib" before drinking the new wine. (This Halacha is subject to several conditions, which we will not address in this context.)
Normally, it is preferable for one person to recite a Beracha on behalf of everybody else at the table, who listen to the Beracha and fulfill their obligation by listening. Thus, for example, it is customary for one person to recite Kiddush for everybody at the table, and this is preferable to having each individual recite Kiddush personally. This is not the case, however, with regard to reciting "Ha’tob Ve’ha’metib" over wine. This Beracha is recited during a meal, when people are preoccupied with eating, and might therefore not pay proper attention to the Beracha. As opposed to Kiddush, which is recited before the meal when everybody can properly concentrate on the recitation, the Beracha of "Ha’tob Ve’ha’metib" is recited when people’s minds are on their food. It is therefore preferable for each person to recite "Ha’tob Ve’ha’metib" individually over the second wine. In fact, some Rishonim (Medieval Halachic scholars) maintained that even if one listened attentively to somebody else’s recitation of "Ha’tob Ve’ha’metib," he has not fulfilled his obligation. Halacha does not follow this view, but it is nevertheless preferable for each person to recite the Beracha individually.
There is a debate among the Rishonim as to whether one recites this Beracha anytime he drinks two kinds of wine, or only when this occurs in the context of a meal. The Rambam (Rabbi Moshe Maimonides, 1135-1204) and some other Rishonim indicate that this Beracha is recited only during a meal; if people get together to drink without eating a meal, they do not recite "Ha’tob Ve’ha’metib." Other Rishonim, however, disagree, and require reciting this Beracha whenever people drink two kinds of wine, and this is the view accepted by Hacham Ben Sion Abba Shaul (Israel, 1923-1998). Hacham Ovadia Yosef, however, in his Yabia Omer (vol. 9), rules that one should not recite "Ha’tob Ve’ha’metib" over wine outside the context of a meal. It is therefore advisable not to recite a Beracha if one drinks two kinds of wine outside the context of a meal, in order to avoid the possibility of reciting an unwarranted Beracha.
It should be noted that wine drunk for Kiddush is considered as having been drunk as part of the meal for the purposes of this Halacha. Even though one drinks Kiddush before the meal, since it is drunk just prior to the meal it can be considered the first of two kinds of wine drunk during the meal. Hence, if people recited Kiddush and then brought a different kind of wine to the table, they would recite "Ha’tob Ve’ha’metib." This applies even if Kiddush was recited over grape juice. Since one recites the Beracha of "Boreh Peri Hagefen" over grape juice, it is considered wine even for purposes of the Halacha of "Ha’tob Ve’ha’metib."
Summary: People who drink two kinds of wine during a meal recite the Beracha of "Ha’tob Ve’ha’metib" over the second kind of wine. Kiddush counts as the first wine drunk at a meal, and grape juice is considered wine with respect to this Halacha. It is preferable for each individual to recite the Beracha of "Ha’tob Ve’ha’metib" personally, rather than having one person recite the Beracha on behalf of the others.
