I just finished up a Brandbook (24 pages) for a new client of mine. Had the agency owner ask me about adding certain graphics or marks to the book. You want to show the logo in "most" all of it's forms, but leave some space for something to be labeled as "MARKETING USE ONLY".
New opportunities will come up that will present an idea to take your mark and move it a bit (sometimes quite a lot), but from the outset, you want to be more hardline to keep all of the lieutenants "in line" so that your launch is consistently used. Only later, you can begin to showcase how logo elements can be adapted as new situations arise.
Take a peek at this little logo and how it continues to be adapted today.
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NOTE:
The iconic script logo for Coca-Cola was created in 1887 by Frank M. Robinson, a bookkeeper for company founder Dr. John Stith Pemberton.