From last year November I have been using the large sky scrappers 300 x 600 in my blogs. At first when the ad was available I was very excited about it and thought that it would give a lot of clicks. I was also hoping to get clicks at high CPC. But I was disappointed there hasn't been any significant changes in my earning. Everything is the same. And that big ad unit sometimes look ugly. And at times there is only one ad and the remaining space is blank. Now what should I do ? Go back to my old 160 x 600 ads ? And this big ad unit also lacks in image ads . Please suggest. Thanks
Seems this is a new kind of banner. I haven't seen it, but I found a reference in Adsense help: http://support.google.com/adsense/bin/answer.py?hl=en&hlrm=es&answer=9739
300 x 600 seems like it would be too big. It would be more of an eye sore than anything. Different size ads work better for different sites. There are a lot of factors in play such as the niche, theme, ad placement etc. The only way to really know what works best for your site is to try different banner sizes, placements and see which gives the best CTR.