I'm in the middle of a major overhaul to one of my sites (mostly due to some CWV issues which really can't be solved without making some big changes).

I figure as long as I'm doing this, I might as well take care of some long-standing ad placement issues which have plagued this site. (Like losing the top 728x90 leaderboard).

I admit though, other than occasionally adjusting placements with poor viewability, I don't often tweak placements to maximize perfromance.

What placements work best for you? What works worst? If you were redesigning your layout today, what would you to maximize your AdSense CTR, Active view, etc.?