I have tried a number of filament holders.
I use one that is similar to this but prints all in one piece and is sturdier:
http://www.thingiverse.com/thing:293623
I could not find the one I use for some reason. I have had only one issue where the spool unraveled some and messed up a print. I added a front feed guide to mine to try to keep the filament near the center of the roll. I created the feed guide adapter for the front of my current holder in tinkercad. It is still early so I am not sure if it will work but I think it will.
I usually don't print overnight if I can help it. For the big prints I wait until the weekend or if I am off. I usually keep an eye on things but can't be hovering over the printer for 6-12 hours straight. 
I was thinking of trying a style like this.
http://www.thingiverse.com/thing:283656
I would also be interested in peoples experiences with these and if there are any recommended ones people use that prevent the filament from "jumping" out of the roll and getting tangled.
DaVinci 1.0A with Repetier .92
Simplify 3D
E3DV6