you could try going to darkshore and running down through to stone talon through ashenville, or go to the barrens (though that has a guard between the border) or you can go to duskwallow marsh and get to the barrens and continue south to thousand needles ( a few lvl 30 NPCS nothing hard) (no guards from duskwallow to the barrens) though barrens is a hostile area (meaning they can attack you but you cant attack them) also you can go through the mountains north of southshore into alteric across the lake into tristfal glade area.
You can always go into Horde territory, you just can't really go into their towns. Many horde countries have bases and outposts with mid-level guards. To pass, simply just run your fanny off until the guards lose aggro.