Marie: Based on your posts so far, I'd vote with Doug for the train. This assumes you're just thinking of the car as a way to get from point A (Florence) to point B (Nice).I've done that route by train and done Pisa to Cinque Terre by car (a mistake driving to the CT, now that's where you want a train). The drive isn't as scenic as you're thinking, I know there's a natural tendency to think that a coast drive like that would be scenic, but the problem is that the most scenic part of the drive is the coast of the Cinque Terre, but from the autostrada you'll see none of that, because the autostrada cuts way inland at that point. The other scenic part of the drive is from Pisa north up past Carrara; the train from Florence to Nice would probably be through Milan, so you wouldn't see that stretch by rail. After the CT, between the CT and Genoa, it's disappointing how far the autostrada runs from the water. The most likely train routing (unless you deliberately choose to route through Genoa) is for the train to go from Florence inland and north to Milan, then south to Genova, hitting the coast. After Genoa, the train tracks and autostrada pretty much parallel each other and give you about the same view (except for the driver), in fact, at times the train goes closer to the coast than the autostrada. Obviously, driving gives you the flexibility to get off the autostrada, but there's nothing in your post so far to indicate that you're interested in the kind of scenic deviations and extra time (extra day or two) it would take to exploit the advantages of a rental car in that way. And, as Doug points out, renting the car involves some complications that are avoided with the train. On the other side of it, with the train you're talking tickets for five (with some discounts for the kids, etc). So if cost is the main thing, you could price both the train and car and compare.
