So I managed to get my shadow priest to level 90. This post is a little bit late as I actually got there last Thursday. So far, the shadow priest continues the trend from Cata of being my fastest character to level, finishing the 85 - 90 stretch in 20.5 hours. That also surpassed his speed from 80-85 in Cata by about 1 hour, although unlike Cata, this time I completed both of his professions while leveling as well (although, honestly, with Alchemy, they've made that incredibly easy this time as long as you start with a nice sized supply of crystal vials).
I'm now back to focusing on the holy paladin. I also did a little bit of work gearing up the shadow priest over the weekend. I stocked him with epic chest and gloves and managed to get a few drops from heroics, but so far have found him to be pretty unlucky with the heroic drops. He's still sitting 2 points short of being ready to queue for LFR.
The paladin recently hit 87 and is off to Kun-Lai. The druid is up next after the paladin and after that will be the mage. I don't think I'm very likely to hit my original target of having all 10 existing 85's to 90 by Christmas, but I'll be fairly close.
I'm also anxious to try the new LFR raid instance after the servers come up later today. The one thing that my warlock really still needs is a weapon, and there appear to be options on every boss in the new instance.