For a healthy, reformed view of the “New Heavens and New Earth”, I would recommend “Surprised by Hope” by N.T. Wright. I’m reading it now and, boy, it’s so good. Our theology of heaven is often confused with Greek mythology along with a plethora of gnostic ideas that we get from ‘Left Behind’ and other such popular works. Wright is a little tricky on some of his theological views (like justification and his interpretation of Paul), but by and large you won’t find any of that in “Surprised by Hope.” The book basically outlines for us a demythologized version of heaven that’s rooted in Biblical exegesis, and a robust, covenantal, eschatalogical view. I recommend it highly.