I voted 60-100% - I usually call it a day now on the European map at 60%, but on the VI map, I do like to take it to 110% and grab everything, including the Viking lands. Like most people I find the "early years" to be most fun and most challenging, and usually given the choice of plugging on with an inevitable victory for my humungous, fully-teched armies led by 9 star uber-generals or scratting around in a single province with two bent sticks, an inbred king and some urban militia, I'll take the latter