The Pasuk in the Book of Debarim lists the seven special species of Eretz Yisrael, known as the "Perot She’nishtabeha Bahen Eretz Yisrael." This status has important Halachic implications. Namely, if a person is eating two fruits, one of which is among this group, then he recites the Beracha over that fruit. For example, if a person is eating an apple and grapes, he recites the Beracha of "Boreh Peri Ha’etz" over the grapes, and that Beracha covers the apple, as well. Even if he likes apples better than grapes, he nevertheless recites the Beracha over the grapes. Since grapes are included among the special species of Eretz Yisrael, they take precedence even over fruits for which one has a preference. The same is true if the grapes are sliced, such as if one is eating an apple and some fruit salad with has sliced grapes. Even though the apple is whole and the grapes are sliced, he nevertheless recites the Beracha over the grapes, because the status of the seven special species overrides the factor of "Shelemut" (wholeness).
If one is eating two fruits from among the special species, then precedence is given to the fruit that appears closer to the word "Eretz" in the Pasuk. The Pasuk reads, "Eretz Hita U’se’ora Ve’gefen U’te’ena Ve’rimon Eretz Zet Shemen U’dbash." The word "Eretz" appears in this verse twice, and the fruits mentioned in close proximity to either instance of this word take precedence over the other fruits. For example, if one is eating both olives and grapes, he recites the Beracha over the olives, and this Beracha covers the grapes. The phrase "Zet Shemen" (olive oil) appears immediately after the second instance of the word "Eretz" in the Pasuk, whereas the word "Gefen" ("vines") appears three words after the first instance of "Eretz." Thus, as the olives are mentioned in closer proximity to the word "Eretz," they take precedence over grapes. Once again, this applies even if one personally prefers grapes, and even if the grapes are whole and the olives are sliced. Likewise, if one is eating grapes and dates, he recites the Beracha over the dates. The word "U’dbash" ("and honey") in this verse refers not to bees’ honey, but rather to dates, and this word appears two words away from the second instance of "Eretz." Therefore, dates are regarded as more prominent than grapes, and thus the Beracha is recited over the dates. As mentioned, this applies even if the grapes are whole and the dates are sliced, such as if one opened the dates to remove the pit and check it for insects. Even though the date is not whole and the grape is, one recites the Beracha over the date and this Beracha covers the grape.
(Based on Shulhan Aruch Orah Haim 211, and Yalkut Yosef vol. 3, pp. 255-261)
Summary: One who eats grapes and an apple recites the Beracha of "Ha’etz" over the grapes, because they are among the special species of Eretz Yisrael, and this Beracha then covers the apple. One who eats grapes and dates recites the Beracha over the dates, and this Beracha covers the grapes.