The lowest level instance for alliance is the Deadmines in Westfall, at 17+ (Though a healer can probably get a group at 15, and tanks should at least be 20.). The Stockade is level 24+ i would say, and I believe Blackfathom Deeps is 21+ or so.
The Deadmines drops a lot of good Rogue gear, some Warrior/Paladin stuff, and a very nice caster staff.
It's not that unfortunate that Alliance have no RFC, nothing good drops in there that you'll keep for more than a level or two, and those levels go by FAST.
Edited, Dec 6th 2006 5:54pm by Vayra