I'm alternating leveling my toons by planet. So far have a:
50 Female Sith Marauder
31 Male Jedi Sage
31 Male Jedi Guardian
26 Female Scoundrel
26 Male Commando
26 Female Sith Assassin
26 Male Sniper
26 Female Mercenary
Leveling my 26s throught Tatooine at the moment. Got the 2 31s out of there already (including doing the bonus series). Then it's leveling them through Alderaan. Doing the Nar Shaddaa bonus series after Alderaan. I'm doing everything except PvP, heroic quests, and flashpoints. Takes me about 8-12 hours per planet depending if I skip dialogue or not as well as putz around. I can do a planet every day or 2. So takes me roughly a week to 10 days to go from my Sage to my Mercenary and start over again. One thing I have noticed is that every time I go through a zone with a new alt, I find something new whether it be a datacron (it's rare if I intentionally look for them while leveling), a lore object, or even a quest out in the middle of no where that only like one class goes anywhere near.
Must admit, I'm enjoying leveling in SWTOR more than WoW. Even with the shared quests, the class stories offer enough variety for me to keep interested. Maybe after these 8 are 50, I'll reroll on another server and play the opposite sex, alignment, and maybe advanced class.
Only my Marauder is dark side. The rest are light. Guess that'll depend how much I can do once everyone is 50. If I can't do anything (as is the case currently), I level alts. But that'll only hold me over for so long. I'll probably have all 50s by mid to late March, give or take, at the rate I'm going.
By then, patch 1.2 will be out.