One of my guildmates is currently in the process of leveling his 6th toon to 80. A rogue. After he's finished with this one, he's planning to work on a warlock - then he's done. So he say. That will give him a Shaman, Druid, Warrior, Paladin, Death Knight, Rogue and Warlock. No Mage, Hunter or Priest.
So we were asking why abandon the other three classes. The answer was pretty interesting. No mage and hunter, because he will already have an other ranged dps option with the warlock. No priest, because he already has three other healers.
I'd personally feel like I had an incomplete set without getting those last three, but in some ways, I also see his point. This guy also spends a lot of time on end-game raiding with his other toons, so leveling even more would obviously distract significantly from that. While I'm not much of a raider, I do enjoy PvP a lot - mostly battlegrounds and world PvP, but some arena as well. So it gets me to wondering if it would be easier to limit myself to a number of toons that I could maximize and not worry about "roles" that I already have covered. Something to think about. It does raise the obvious question - once you get a toon of each class to 80, what then? I think you're still picking one or two "mains" and working on maxing out their gear - whether it's raiding or PvP. You can't possibly give adequate play time to 10 different toons.
Which all has little to do with the topic of leveling strategies. The above mentioned guildmates approach has been to level each toon to 80 - one at a time. It' s a very focused approach and obviously very successful. If you're attempting to level a large number of characters, I wonder if there is a more efficient approach. It's the approach that I've mentioned before of leveling each character a set number of levels (4? 6? 10?) then parking them in an inn to accumulate rested xp, mailing the BoA pieces to the next toon and more of the same. It seems like this would maximize your rested xp bonuses while also providing some comfort to the ADHD issues that many of us alt addicts have. We can only pay attention to one character for so long before we get bored and move on to another. For many, that often means creating a brand new character somewhere and leveling them from scratch. But what if you had a toon, fully rested, with BoA xp bonuses just mailed to them, that you hadn't played in - oh - say 7 or 8 toons. Something new, something fresh, and something that you can park back in an inn after a few levels. I'm sort of liking the idea of going 1-10, then 11-20, then switching every 6 levels after that.
The downside is, my teenage son desperately wants me to power level my druid to 80 to do arena's with him, so my plan at testing this strategy might be on hold for a while. I'd also need to decide what to do with my hunter - wait until all the other toons catch up, or pop him in the 6 level rotation, just realizing that he's going to get to 80 first. Take him to 32 then have him wait for the other toons to catch up, or just let him run from where he is.
See, this is the downside of maintenance days - I have way too much time to sit and think about these things rather than just hopping on my toons and leveling them! Oh well!