Why did Yosef want his brothers to settle specifically in the land of Goshen?
Rashi: It contained ideal grazing-grounds for their vast amount of flocks.
Da'as Zekenim: Pharaoh had given it to Sarah. This is why Yisrael desired it, and received it, and the Egyptians did not protest.
What made Yosef so sure that Pharaoh would designate for them the land of Goshen?
Rashi: He was sure that, once Pharaoh knew that shepherding was their sole area of expertise, he would settle them there, away from the main areas of Egypt, because the Egyptians, who worshipped sheep, despised the shepherds who looked after them. 1
Rashbam, Da'as Zekenim #1: The Egyptians despised shepherds who raise Tzon, which they considered disgusting.
Abarbanel, Sifsei Chachamim: They consider shepherds holy, and will settle them in the best part of Egypt.
Both Targum Onkelos and Targum Yonasan translate "To'avas... " as, 'they kept their distance from them.' Riva, Hadar Zekenim - They despise shepherds, for they hit the flock with sticks. Riva - Also, they know that shepherds know that there is nothing [divine] about Tzon. Also, they benefit from the Tzon; they drink the milk and use the wool. Although some say that "Ro'eh Tzon" means they eat the Tzon (Hadar Zekenim, Da'as Zekenim #2), Riva writes that the verse connotes unlike this.
How can it be that the Egyptians despised shepherds? We find that the Egyptians themselves had flocks in Makas Dever (Shemos 9:3-6), and that Pharaoh had flocks (Bereishis 47:6)!
Moshav Zekenim: They would not allow flocks near them; only far away, in the field.