If you don't have a booster, probably go with a chain:
A >> B >> C >> D >> E

Ideally level a tank type toon in the first set, on account A.
Level 61-62, with a lot of the Hellfire gear will be a decent tank for lower content.
So even if you're not a geared 80th, you can boost subsequent toons through Scarlet Monastery... which gets you 1st to 45th in a relatively short time.
Then you can have the tank type help them run quests or whatever.

Boosting will still be your best bet for leveling.
You just won't be able to boost to 60th or whatever.

Once you get a bunch of teams to 60th, mess around with the granted levels.
Cascade granted levels won't work out into full toons across the board.
But you'll get a toon on each account (except E) for every two that are leveled.
If you were to level a team, use it to boost three more, and then level grant two toons per account, that's a decent start.

Definitely have a team which will be decent for PvE.
Ideally, this team will level first, run a bunch of heroics and get PvE gear, so they can do heroics fairly quickly.
Then run heroics for heirloom gear.
Specifically the 10% experience (badge) chest piece.
Depending on how often your faction controls Wintergrasp, also pick up the 10% experience (Stone Keeper Shards or Badge) shoulders.

I went with Cloth Chest/Shoulders (caster stats) and Leather Chest/Shoulders (melee stats).
I don't really mind Hunters or Death Knights wearing leather chest/shoulders; the armor blows, but the stats are relevant and the bonus experience is all I care about.
If you don't have the patience for both cloth and leather BoA gear, go with cloth only; with 5x toons, you'll level way faster then with plate chest/shoulders and no 20% experience bonus.