I haven't played as alliance post-Cata, so I don't know what the experience is like there. But on the horde side, the quests in Silverpine, Ashenvale, Stonetalon, and South Barrens all centered around the war vs the Alliance. Maybe some of the other zones, too, I haven't seen them all yet. Desolace has at least a little of it, too, where you get to raze Nijel's Point as a firestorm (not that most alliance could even pinpoint Nijel's on a map).

I've heard that Swamp of Sorrows has an alliance quest line where you destroy Stonard. I suppose that otherwise, with Southshore gone, there aren't many spots in the eastern kingdoms where horde and alliance are directly interacting.

Aside from the conflict with the alliance, one element that appears in the questing that you didn't really get from vanilla is a sense of danger or urgency in the storylines. Like, we're under assault and you need to do this [b]now[/b] to save us! As opposed to, eh, kill some boars and get back to me when you're done. It makes the quests more compelling, IMO.