Ph.D, Ed.d or Not at all?

My question is; Should I work on my Ph.D,Ed.D, or not at all? Background to this question is that I am already a library director albeit a small univeristy library, I do want to teach, but I would prefer to stay at this location till I retire. I have relatively young children so I could wait about 10 years till they are "out of the house" and in college.