At the moment, I am only using channels to track my Adsense units from different websites. That's about all. I have not tried using location-based channels to track them yet since I don't get all that much clicks.
I use channel to track adsense unit by location. I'm not sure how this may help to increase site visits but I feel it's probably for my own knowledge to know where my visitors come from. It is also possible to setup channels based on Ad size but I'm sure how this works to help. Anyway, traffic to my site is rather low so I feel there's no need for that at the moment.
Ya even i do the same thing i use channels based on location and size of banner . I mean a square or a banner or something like scroll bar banner. Thts the best thing i feel. You can see where you are getting good amount of clicks and according to that place banners or boxes in that particular area. And that does work.