Ambrose writes well so his trilogy on WWII is good even if he includes iffy info at times. With the Old Breed is essential, Naples '44 gives you an interesting perspective on liberated Italy (starving Italian women do some things for a bit of food), Rick Atkinson's liberation trilogy on the war in North Africa and Europe (An Army at Dawn, The Day of Battle and The Guns at Last), Ian Toll's trilogy on the Pacific Theater (Pacific Crucible, Conquering Tide, Twilight of the Gods), Richard Overy's Russia's War and Why the Allies Won, anything by Antony Beevor (dude can write), Alex Kershaw's books are really good and readable, The Storm of War by Roberts is a good overview as is A War to Be Won, Hasting's Overlord, maybe something by John McManus, Miller's Masters of the Air...that's a good start. And then there are individual battles and biographies. See you in a couple of years.