Charles Martel and Charlemagne

[Hasdrubal]

I know this is a bit off topic from ancient warfare, but as someone who's only familiar with Greek and Roman History I would like to start expanding on my knowledge into the medieval periods. Two people that are very interesting to me is Charles Martel and his grandson Charlemagne. I guess what's peaking my interest is Vikings. Even though I was told Vikings is no where near what actually happened, it's at least *piqued* my interest in those surrounding times. 

I suppose what I'm asking is books for those people, including the era that those men, including the Vikings, and the Saracens. I'm looking for good authors that match that grip the imagination like Thomas Asbridge, and Adrian Goldsworthy. Anyone have any recommendations?