Hey there,
Thought I'd get the discussion started...Hopefully! I'm using tag manager more and more. I'm really enjoying the debugging interface and the layers you can apply onto events/actions. I've yet to use custom variables in tag manager though, so would be keen to hear about how people have got on with this.
I'm a big fan of goals and solid ecomms tracking. However, one thing that I have noticed which causes a bit of tension is event tracking labelling. For action, I often put the verb, e.g 'played/watched/clicked' and for label the filename/video name etc. However, some GA event tracking plugins and documentation track the filename as the action and label as the verb. I'd be keen to hear if anyone has a preference one way or the other! It feels kind of wrong to put the label as the verb, but I'd definitely change my mind if there was a compelling argument.