how long is the drive from rome to venice?
Driving Rome to Venice is all motorway (not for free, unfortunately). It is excellent road, but it may get hectic during peak season, on weekends and in certain other periods of the year (e.g. Easter holidays). It is actually about 600 Km from Rome to Venice, which means at least 5 1/2 hour non-stop. I think - which you probably already did - you should take this as an opportunity for seeing a bit of the country as well. Stretch your legs say every two-three hours.