For Gettysburg, I enjoyed Trudeau's "Gettysburg: A Testing of Courage"
I have not had a chance to read all of Harry Pfanz's three books on the battle, but the two I have read have been very good as well.
Stephen Sears has a book on Gettysburg that I have not read, but if you have read any of his other books, you should enjoy Gettysburg if you enjoyed the others.
However, I would also recommend reading a book on Fredricksburg, then Sears' "Chancellorsville" before reading his Gettysburg as you cannot study the Gettyburg campaign oustide of the context of the events of Chancellorsville, which are linked to Fredricksburg. I find it better to study the "phases" of the war, not just individual battles. For instance, the series of events from the Peninsula, to Cedar Mountain, to Seconod Manassas, to Anteitam, to the armies settling in at Fredricksburg are all one string of highly related events that cannot be truly appreciated if they are not all studied together in context. Likewise the battle or Fredricksburg, the Chancellorsville campaign, then Gettysburg and the retreat back to Virginia are all one big group. Then the Wilderness to the seiges of Petersburg and Richmond are a phase, with the last phase being the breaking of the seige lines to Appomatox. I believe that we can study any of those "phases" together on their own and understand them, but to study any single battle from one of those without first having an understanding of the strategic developments leading up to it takes away from the experience.
But I digress!
And while they aren't covered by any HPS or BG games (YET?!?!?!?), the overland campaign of 1864 has no equal than the writings of Gordon Rhea, whose four books (so far) on the subject are deserving of any award currently available to mankind.
Regards,
Captain Alan Lynn
3rd Battery "Jacksonville Greys"
4th Div, II Corps, AoA
God bless <><