Hi!
I've searched aroudn for a background book for WIA and was very near to buy John Ferling "Almost a Miracle" which has great reviews
http://www.amazon.com/Almost-Miracle-American-Victory-Independence/dp/0195382927/ref=pd_sim_b_5
But by chance found a second hand copy of "Rebels and redcoats" by Scheer & Rankin
http://www.amazon.com/Rebels-Redcoats-American-Revolution-Paperback/dp/0306803070/ref=sr_1_1?ie=UTF8&s=books&qid=1242313689&sr=1-1
on a used books shop in Madrid
just for 4 euros
Couldn't say no!
I have only read some fragments of it still, but i really liked it.
It's heavy on first hand accounts from both sides and all levels (for generals to soldiers) that are interwoven with a excellent narrative of the war.
It has good maps and lengthy and lively descriptions of the battles.
Maybe its not very "scholar" like but its very readable and detailed.
Cheers