Recently I've been (slowly) reading the following books. Both are highly recommended.
Of course the companion to these is the original source. I really like the Landmark edition with its maps, pictures and articles.
Most of my readings of Marathon, Thermopylae, Salamis and Plataea were very wargames focused - high on tactics and strategy but lacking much of the historical context. It was therefore to remind myself just how tenuous the Greek states were, especially Athens. Also despite knowing how the film turns out, it is clear that the result was very much up in the air and the odds favoured the Persians.
Time to haul out the 1980s vintage ancient Greeks methinks.