netmeg - 6:10 pm on Mar 28, 2013 (gmt 0)
I'm still trying to find my best combination. For years I ran a 468x60 just above the content and 300x250 in the sidebar; Google sent me an email predicting a revenue increase if I swapped out the banner for a 728x90 at the top, and darned if they weren't right - CTR and revenue improved immediately. On extra long pages, I have a 468x60 at the bottom too; I might swap that out for another 728x90 and try that.
Link units used to work really really well for me, but they crashed last year almost across the board. Not sure why, but I took em all off.
Right now I'm back testing borders again. I just hate how they look, but if they work, they work.
I probably should test plopping an ad in the middle of my content, but I just haven't been able to bring myself to do it yet.