you can zone into Ragefire chasm at level 8, but that probably isn't feasible for Alliance. Deadmines is level 10, and Stockades is 15, so for ally, I'd go there before going all the way to SFK, unless you want any of the gear from that dungeon. After that there are so many good options, you could go to BRD at 40, or ST at 35, and go all the way to 60 there, but boosting will get very tough past 40, even for a 60. Probably better off playing a whole team normally at that point.

so that would be:

1-10 normal grinding, maybe mob tagging with the alt then nuke with the 60?
10-15 Deadmines
15-21 Stockade
21-30/45 SM (can go until you are sick of the place)