Rhone Valley in March

I'm not interested in wine (isn't your daughter going be bored?), but from looking at a map I think the Rhone isn't really within day-trip distance of Paris. The fastest way to get to the area is probably the TGV to Lyon (northern part) or Avignon (southern part), then rent a car, or you could switch to a TER train and get to the smaller cities that way. The bulk of the ride will be on a TGV, and those train tickets become very, very expensive as the travel date approaches. Current round-trip fares for March 12 seem to range from 50 to about 200 euros per person. The lower-cost options will disappear as the tickets are snapped up by other travelers. Check schedules and fares on sncf.com.

I'm also not sure what sort of weather to expect there in mid-March, but I don't think chilly and rainy can be excluded as possibilities. You can check historical weather data on wunderground.com. I've linked the March 2017 data; scroll down for the temperature graph. Data is available for about 15 years. On average, Lyon has 8.4 rainy days in March, according to the summary weather chart on its Wikipedia page.

The Rhone Valley is indeed a lovely place but you have a few things to consider. First, March is the time of the Mistral Winds https://en.wikipedia.org/wiki/Mistral_(wind) , a wind which blows about every third day. Having lived at the southern end of the valley, believe me that you don't want to be out in these winds if you have other options. Strong, icy, straight out of the Alps.

Second, the Rhone wine region has two main parts, the northern denominations, which begin not far south of Lyon and the southern end where you find Chateauneuf du Pape. You could conceivably take a TGV train to Lyon in two hours, rent a car, and set out from there. Perhaps, some of the wine buffs could tell you about organized tours from Lyon or the best vineyards to visit. Personally, we're big fans of Rhone wines but have never gone tasting. When we're in the area, we hit the extensive Roman ruins.

Just cross your fingers it's not a day the Mistral is blowing. If it is, your daughter will let you know what she thinks of your plan in no uncertain terms. Consider the Champagne region, an hour to Reims by TGV, where there are no winds.

I am starting to feel like a broken record, but Lyon would be a great place to include on this itinerary, and of course it sits at the confluence of the Rhone and the Saone. Just 2 hours from Paris by train. You could rent a car from there to go further south.

It is a fabulous city with something for everyone, check it out in your favorite guidebook.

Id take a train to the TGV Station outside AVignon. Rent a car, do 2 nights and drive to all the cute towns.

Doesn't the mistral sometimes hit Provence at that time of year? Or perhaps there are some areas that are safe from it.