I had a similar problem myself. I've had two account. I bought two collectors ed, day one. I opened one, later on that spring i finally opened the other (thou my friends kept telling me to ebay it, but meh). Moved my 60 mage over, so i had a 60 mage and shaman duo. I then rolled a warrior to 60, a hunter and a warlock. These were all horde. Luckily around the time I finally decided to start my 5-boxing, my friends decided to all jump alliance. So now i have a fresh start with only a 56 hunter on a pvp realm i'll never move.
My 2 cents is I would just right down a setup of what you want to play and stick to it unless your either: getting bored with it, its not working well, or some really good reason. I ended up doing this to come with my pally, priest, 2 warlock and mage combo. Once I get those to 70 i'll prob roll out a shaman and possible try to fit it into replacing a warlock or just as a fun alt.