frankleeceo - 4:00 pm on Nov 10, 2013 (gmt 0)
not really any solution, it's worst because advertisers bid less for that size ads in general.
you could however get that ad unit additional eyeball time if you place navigational menus adjacent to that unit. But that eats into your useable content areas.
but if you have that much space to either side of your page, a 300x250 usually performs better. I assume you use those units as pure display and not going for targeted text in-content.
I would personally combine the use of 300 x 250 + leaderboard banner + 160 x 600 to get the most of bids for each individual sizes, placed on your most visible locations to garner the most attention and potential clicks.