Preface: I am very far from an expert on Nazi Germany! However,

I've always found Ian Kershaw's Hitler 1889-1936: Hubris (the first part of the his massive two part biography) very persuasive in the way it analyses and conceptualises the workings of the Nazi state (the pre-war nature of which obviously also appears in Vol.2). In particular, Kershaw's notion of "working towards the Führer" (something that he had been developing since at least the early 1990s. See for example his 1993 scholarly article '"Working Towards the Führer", Reflections on the Nature of the Hitler Dictatorship', Contemporary European History, 1993, 103–118) as a way of understanding exactly how governance, politics, and repression worked within the Nazi system. As I noted, though, I'm far from an expert in this stuff and I'm sure those with greater knowledge of historiography will be able to provide more in-depth recommendations.

Malcolm