There's a couple of books I recommend, if your going to Loughcrew when in Meath (there's no good excuse not too!) then 'The Stones of Time' by Martin Brennan is half a great read, the accounts of the observations in Loughcrew and breaking in to Knowth are truly fascinating but the interpretation part of the book lost me after about three pages.
http://www.amazon.co.uk/gp/product/0892815094/026-4424955-0986842?v=glance&n=266239
'Inside the Neolithic Mind' is also quite thought provoking, it deals with the tail end of the mesolithic and beginnings of the neolithic with well made arguments though it only touches some sites in Turkey and the east and west coasts of Ireland. The section on the Boyne Valley is particularly good.
http://www.amazon.co.uk/gp/product/0500051380/026-4424955-0986842?v=glance&n=266239
Despite his many detractors M. J. O'Kelly's book 'Newgrange: Archaeology, Art and Legend' is much more than an archaeological report, his amazement and awe at the monument and its builders jumps from the pages and his arguments are well made and logical. Read it and make your own mind up, whatever you think of the restoration I haven't seen any other arguments for what it looked like originally made as well as in this book, I really enjoyed reading it. If you come across what looks like its counterpart for Knowth by George Eogan beware, the only one currently available deals only with the later settlements at Knowth long after the mounds had slipped into disuse.
http://www.amazon.co.uk/gp/product/0500273715/026-4424955-0986842?v=glance&n=266239
