How to handle donors who don't ever want first name used?

We have a donor who doesn't ever want the first name used, only a title ("Dr") and the last name.  However we have lots of email merges and snail mail merges using first (and sometimes last) name.

How do other orgs handle this type of donor request?  

Are you using Informal Greeting and Formal Greeting in merges rather than the first name field with the Auto Name deselected on specific households as needed?  Or do you have another way of handling this type of request?  

Any thoughts or suggestions appreciated!