I always assumed the referral type for banner/display ads would be "Other Website"...is this correct?
Second Question: We did some advertising with a vendor and they drove a very high amount "typed/bookmark" traffic. Is there any other sources in the "typed/bookmark" traffic besides some email, typing in our site directly into UR, or bookmarked tabs?
Are there any redirects that happen before the user reaches their final page? If the campaign has a vanity url or go-code that redirects before a page load occurs, then the referring domain will usually be lost at this stage, as the landing page will think it was the redirect that is the referrer, rather than the original referring domain.
Similarly, if your banner/display ads are directing users to a redirect, the referrer will probably be "typed/bookmark" too unless your redirect is preserving the original referrer in the browser.