I have upgraded clients and sat in a lessor class of service more than a few times. It pays off in the long run especially if the client's firm does not allow paid travel in a higher class of service. At that point it becomes a treat for the person who is usually obligated to economy class.

I don't brag about my AA status in any case.

And if someone says 'why bother with the miles?' I really try to keep quiet on the subject.