If you are a large site adding ad units to your site, or just wanting to check the setup of your site is the best you can do, then our ad size guide is for you.
As with small sites, having the three IAB Standard Ad Units (160×600, 300×250 and 728×90) is essential, however with more traffic comes more potential revenue so you should also possibly experiment with other ad sizes.
To further monetize your users’ eyeballs (which is a disturbing yet accurate description of what online advertising attempts), there are many ad size options available to you. Using multi-size ad tags is likely a good idea, and many sites like the 300×600 as it can combine with either the 300×250 or 160×600 to create a high value add space.
Adding reskin capabilities to your site for homepage takeovers or sponsorships is also a great idea, and assuming you have the inventory pre-rolls and mobile ads are also likely a must. Overlays can be great money-spinners too, but deciding whether or not your users will tolerate such things is up to you.
As always we can only really recommend you to take a look at the information provided and work out what is right for you. Our rule of thumb is to annoy your users as little as possible, however, you have your own thumbs of course and therefore can make your own rules.