it depends on the quilt and who/why
i've been known to write a whole story on a label--
i've very much personalized a few- like the one to a wonderful lady with breast cancer who had been through so much during a very long-dreary winter-
the quilts for my family are quite personal-
sometimes i just add the basics, name, date, place, fiber content and care instructions (if it's a quilt that is a sale quilt- i don't know who will own it) but if it's a personal gift quilt they labels are normally much more involved.