I recommend Mind of Clear Light: Advice on Living Well and Dying Consciously by His Holiness the Dalai Lama (translated by Jeffrey Hopkins).
We could all stand to take his advice on being aware that death could come any day to live more fully every day.
Of course, this is a translation and explanation of a seventeen stanza poem by the First Panchen Lama
so the later chapters in the book discuss more and more esoteric Tibetan Buddhist ideas.
I will share a copy of the poem sometime.