I second this advice. I leveled my first horde character (monk) when I resubbed last month and it was pretty fun leveling entirely through BGs. When I hit 120 is when I felt defeated because of the grind.
If I resub prior to SL (which I very well may because I have a bit more free time), it would be to level another horde character via BGs (probably hunter).
If you’re interested in this, I asked the community for advice about the leveling-via-BG route and posted the info here: Leveling Via BGs for Fun PVP
I can update my original post with the advice I found most useful.