I am working through the 8th Doctor books not in order of internal continuity, but in order of popularity on LibraryThing (in the hope that I will thus discover some neglected gems towards the end). I'm afraid I didn't get a lot out of Alien Bodies. I liked the vignette of the Third Doctor and Sarah Jane Smith burying Laika at the very beginning; and I applaud Miles for bringing back and making effective the Krotons, of all unlikely Old Who baddies, half way through.
But as so often, I stumbled on the means and motivation of the villains - in this case the Celestis, with quasi-magical powers including over the afterlife, squabbling with an unlikely assortment of bidders over the Doctor's corpse (from way ahead in his own timeline). I understand that this book is the basis for Miles' own run of spinoff Faction Paradox, so I understand why he was trying to do this, but didn't quite get what he was trying to do.
Sam Jones is the initial companion in the Eighth Doctor Adventures, and this is the third novel I've read featuring her. Miles strives to inject her with some extra background and cosmic significance, rather as the Old Who writers did with Ace in the last season in 1989 (the parallel is made explicit). This looked at one point like it was going somewhere interesting, but wasn't really resolved; I hope it will be in one of the other novels.
In summary, doesn't really seem like essential reading to me, but maybe its significance will become more obvious as I work through the series.