One thing I have been enjoying in my Kobo version, published by Thomas Nelson, is the brief synopsis and historical background, added as supplementary material, that precedes each book. They've not only helped in my understanding but have also piqued my interest in the place and time settings as well as facts and theories surrounding the political realities of certain stories. In the four books mentioned in the above post title, for instance, these were not peoples I'd otherwise have had any knowledge of.
From the same sort of historical interests, I'm marveled at the idea that these speeches and letters are as old as they are.
As for the letters themselves, a few more brief notes:
1. I'm still struck by the messages about women having to be submissive. Egad.
2. Paul seems to try really hard to create symbols, arguably with varying degrees of success. The whole "shield" thing? As the Salvation Army has shown us, that one stuck. But metaphorical circumcision? Not so much.
3. Whereas the gospels came across as the basis of faith, the epistles so far seem to be the basis of the church.
By the way, if you look for Flickr photos to use for Bible related posts, be prepared for a lot of this:
Rubber ducks, less typical: