I think the best way to optimize adsense is to look how big sites like digg and technorati do for optimization they may differ from your site in colors so search for similar sites as yours but more famous aand find how they place ads and how they choose colors they must be the best
Just copying the layout / design of big sites alone is not important; what is required is good contents and suitable ad placement. The design of the site, of course, plays some role but next only to the contents