I finally got the carcasses built for the bookshelves and now have then hung in place. I decided after much thought to go with continuous/piano hinges as they afford much more strength along the entire vertical axis than either pivots or traditional hinges. Plus, they cost a whole lot less ($10 per hinge versus $170 per pivot set!), and will appear more asthetic (though not totally hidden) versus traditional hinges.
I also decided that gluing the 1/4 ply into the dado in the rear of the units would provide a whole lot of structural stability for preventing racking. I may add a piece of 1/2" channel iron corner-to-corner in the rear if it looks like I need more bracing.
Next is the trim - I'm going to try and rabbet the moulding around the hinge as much as possible to hide it (I'm using 445). I'll also glue and staple the trim to the top and bottom edges of the units to provide "stops" when closing. I'll send out more pics as I get that step done.
Boy, this has been fun :-)
I've put several pics out on a.b.p.w for your perusal/critique/bashing :-)