I'm not sure whether to post this under historical novels or thrillers, but one of my favorite Vietnam War era novels is free on Amazon today:
http://www.amazon.com/ROLLING-THUNDE.../dp/B0019LNUVA
It's the first book of a series written by Col Mark Berent, USAF (Ret) and the entire series is a first rate account of the air war in Vietnam written by someone who was in the thick of it and is told from the point of view of a combat pilot. Later books in the series do a good job of discussing the war from the perspective of the corridors of power in Washington, the POWs in Hanoi, and some of the special ops soldiers as well.
The series is more than realistic; it's real! I was a ground unit commander and received close air support from his wing. Col Berent and his fellow pilots saved my a** repeatedly.
If you have any interest in military aviation or in the Vietnam War in general, you should read his entire series.