Strategically thinking, though, the Klingons wanted a surprise attack, and were forced by circumstances to stop at DS9. If they had some territory that was actually bordering on Cardassian space, they could legitimately and covertly sail to that territory and pounce on the Cardassians from there, without losing the element of surprise.
The Star Charts
map tries to reconcile with the various dramatic elements by suggesting that Cardassian territory extends "antispinwards" (to the right in the map), just like it does in onscreen charts - but that Klingon territory reaches "spinwards" at the same location, with Betreka as the place where the two collide. And the 18-year struggle over that region left both sides the losers, with the UFP actually becoming the eventual owner.
Those onscreen maps in DS9 show Cardassian space ballooning to the lower right in the Dominion War, in this theory as retribution for past wrongs... But that region is not the Cardassian heartland. In "Way of the Warrior", the Klingons chose the "long route" because they wanted to have the shortest distance of Cardassian-held space between their launching point and Cardassia Prime. And that was the distance between Bajor and Cardassia Prime!