I use Melodyne Studio 3 standalone (ALOT) for all my vocal and harmonies editing, and I generally use the plugin for bass tuning.
Here's my workflow for Vocals.
I have a key command set for "Export Track As Audio File"
And I bounce each vocal track down (takes 2 seconds, I usually just arrow down and hit the key command for Export Track and then enter and repeat.
I save all my vocals in a folder titled "pre vox 182< project tempo" (Its handy to see that tempo on the folder so you can enter it in on the transport part of Melodyne.
Then I MUTE all the tracks I just exported, Now I bounce down the mix of the song with no vocals (make sure the bounce starts at 1-1-1-1. I always name that MIX and put it in the folder of vocals. I like to have the song playing in there while i'm working out all the parts..
Now open a new arrangement in Melodyne go to File>Import Audio File and select all your tracks and push enter.
Tune and Save Audio to export the tuned versions and then drop them back in Logic starting at 1-1-1-1 and your in business.
IMHO Studio is unbelievable because of key commands.. you can FLY if you get a workflow with that going.. the plugin (which i still like) PISSES me OFF every time I freakin push Command Z like a retard... AND because I can make harmonies blend by seeing the layers underneath while I tune other notes..
happy tuning.