There's one reason I wish I was bisexual instead of gay. That is because straight friends of mine love to talk about women and women's bodies. Sometimes I think that's all they think about. But, it's a topic that bores me, because I'm not interested in women's bodies. When they start talking about women and "pussy," my mind wanders and they basically "lose me," until they start talking about something I am interested in. If I did have SOME desire for women, I wouldn't be so bored by talking or listening to that kind of talk. That would make me more able to relate to my straight friends, and thus have closer and more satisfying friendships with them.
Also I guess it would mean I would find more people attractive and thus have more possibilities for relationships, but that seems like a secondary benefit compared to the first.