[phayman53]

My two cents:

Migration Era Europe up to or including Charlemagne in one book and then Charlemagne (or just after depending on the first book's scope) through the viking period would be awesome [Edit: or all that time in one book]. Great potential in those eras for everything from realistic military and/or political campaigns to cinematic and fantasy campaigns.

The world was less populated/more soread out, polities were smaller, politics was very personal, and even military engagements tended to involve less people (therefore the PCs could have a realistically larger impact).