DC really seems to love the idea of having a "Big Three" of Superman, Batman and Wonder Woman, even though Wonder Woman really doesn't compare all that well to the other two. Superman has two ongoings (soon to be three), an All-Star book and a team-up book with Batman. Batman has has three ongoings (soon to be four), an All-Star book and a team-up book with Superman, plus tons of mini-series. Wonder Woman has one ongoing (and, soon, an All-Star book).
I understand that the three characters are the only three DC superheroes who managed to survive from the Golden Age to the Silver Age, but is that a good reason to have a "Big Three?" It's not like it helps Wonder Woman's sales to be part of it (as her sales seem just about the same, regardless of her status in the Holy Trinity).
Marvel doesn't have a "Big Three." Heck, I do not think any other company out there spotlights three characters out of all their characters.
Marvel just lets their most popular characters be the most popular - there is no concerted effort to let you know that these are their biggest characters.
Why does DC find it so appealing?