The book satisfied me until the end of Augustus's reign. I'd like a good MODERN book covering Imperial history, Gibbon just won't do it for me.
I also want to know what happened after Alaric sacked Rome. A proper history on what I assume must be the Dark and Middle Ages with a focus on continental Europe. I am not interested in learning about provincial English nobles in heavy detail, I'd like to see a bit of Byzantium and Al-Andalus, with a huge focus on what went on in Italy since that's still where the action was, with some idea of how France and Germany transformed from rump states carved out of Roman territory by Germanic migrants.
Michael Kulikowski's recent The Triumph of Empire: The Roman World from Hadrian to Constantine (2016) provides an excellent narrative of the late Roman Empire, and I am sure that his forthcoming Imperial Tragedy, covering Roman history until 568, will be equally good. Unfortunately, this period is very contentious and historians such as Peter Heather would narrate the fifth century quite differently - you can check it out for yourself through his The Fall of the Roman Empire: A New History of Rome and the Barbarians (2005). Other good choices would be Peter Sarris' Empires of Faith: The Fall of Rome to the Rise of Islam, 500-700 (2011), which is very up-to-date on eastern events in Byzantium (but is denser than other books aimed at a popular audience), and Averil Cameron's The Mediterranean World in Late Antiquity, AD 395-600 (1993).
For the Middle Ages as a whole, Chris Wickham's Medieval Europe (2016) will give you a very broad overview of this entire period. He is less interested in political and religious history, but if you are curious about more social aspects, this book is definitely for you. For a book that emphasises the role of Christianity, Peter Brown's The Rise of Western Christendom: Triumph and Diversity, A.D. 200-1000 (1995/2011) is fantastic - and it definitely covers a lot more than Western Europe, so you really do get a good sense of what's happening in (European) Christendom as a whole. I'm not so well-read on the latter parts of the Middle Ages, so I'll leave it to the other medievalists to give you some recommendations for that period!