[This is my comment on a post found on Times and Seasons: http://timesandseasons.org/index.php/2009/07/what-death-can-teach-us-about-heaven-and-hell/.]
C. S. Lewis has many intriguing things to say about this topic--or rather this cluster of interrelated topics: why there's a hell, whether it's eternal, whether redemption from hell is possible, what essentially life in heaven and hell might mean, whether heaven includes or allows for association with friends and family, how different heaven might be from life as we know it here, etc. My comment can only scratch the surface of what he has to say (which of course I look at with the coloring and emphasis provided by my Latter-day Saint point of view). I'll give here just a few tidbits.
On family in the afterlife: Besides questioning and deflecting hope of family reunions in the afterlife, Lewis also apparently longed for such a possibility. He wrote in The Four Loves: “We may hope that the resurrection of the body means also the resurrection of what may be called our ‘greater body’; the general fabric of our earthly life with its affections and relationships. But only on a condition . . . : nothing can enter there which cannot become heavenly.” (In LDS terms, a truly celestial marriage could only be a marriage that had become truly celestial.)
On our “small-minded expectations”: “We are half-hearted creatures, fooling about with drink and sex and ambition when infinite joy is offered us. . . . We are far too easily pleased” (“The Weight of Glory”).
How different heaven might be from life as we know it here: By what Lewis calls “transposition,” all (perhaps) that is familiar to us might continue but be transformed and lifted to transcendence. We may “be hardly more surprised by hitherto unimagined differences than by hitherto unsuspected similarities. . . . When I know as I am known I . . . shall see how the transcendent reality either excludes and repels [the categories/concepts/realities I’m familiar with], or how unimaginably it assimilates and loads [them] with significance. Had we not better wait?”--i.e., wait and see. (All this is from “Modern Theology and Biblical Criticism”; see also “Transposition” and much of Miracles.)
On the same question from LDS sources, I just read a verse the other day that blew me away, though I’ve read it many times before: “For since the beginning of the world have not men heard nor perceived by the ear, neither hath any eye seen, O God, besides thee, how great things thou hast prepared for him that waiteth for thee” (D&C 133:45). So we hope for something far beyond our present capacity to imagine. Yet Joseph Smith also noted the similarities: “that same sociality which exists among us here will exist among us there, only it will be coupled with eternal glory, which glory we do not now enjoy” (D&C 130:2).
On “second chances” with implications for friends and family (this is me now, though Lewis has things to say on this as well): If God is love and if that love is essentially and supremely an absolutely unqualified concern for the welfare of others, then desiring the salvation of all (“not willing that any should perish” [2 Peter 3:9]) is part of what it means to be godly. (By the way, one of my favorite definitions of hell is from The Brothers Karamazov: “the torment of no longer being able to love.”)
Given God’s power and love, I believe that all will eventually have as many blessings as they can possibly (which among other things means “willingly”) receive. Any sort of permanent hell would thus require a person’s firm, knowing, and irrevocable choice (I believe this view is supported both by the scriptures and, as it happens, by Lewis). Or perhaps a permanent hell might also result as a person, through a series of choices, undergoes such a change of nature as to be unable any longer (ever) to choose to allow God's redeeming and transforming power to operate. (This last sentence is packed with all sorts of assumptions and speculations--but it does for me hint at what it might mean to be unredeemable.)
Short of these terrible possibilities, both the scriptures and the Spirit suggest to me that there's ALWAYS hope. John H. Groberg gave a talk on that theme that repeats the phrase "there's always hope" 40 times (http://speeches.byu.edu/reader/reader.php?id=6901). I endorse that view and would add, the story’s not over yet and won’t be for quite a while.