We are traveling to the Dordogne and plan on renting a car. We would like to train south after we arrive in Paris and get a good night sleep before renting a car and traveling to St. Cyprien. Any suggestions on a interesting middle size town where we can rent a car an hour or two outside of Paris? We were thinking of Amboise.
Amboise will work, there's a Europcar there. It's about 2 hours by train from Paris that includes a transfer at Tours. Chartres is another option if you're interested in seeing the Cathedral. A little over an hour by train.
The idea of going an hour or two outside of Paris by train and then driving to St Cyprien (if that's the St Cyprien in the Dordogne) is a pretty boring five hour drive. I'm guessing the train ride is about two or two and a half hours to get from Paris to Amboise. You might want to consider taking a TGV to Avignon (less than three hours?) and then driving from there to St Cyprien along the coast and then up past Carcassonne, Albi, Cahors, and then into the Dordogne. You're looking at six hours if you swing through Albi, five and a half otherwise. The scenery is a lot better and the stops more interesting.
A lot depends on which direction you are going from Paris. For Amboise, I don't see a rental car agency in the train station. Avis appears to be a few blocks away and Europcar is across the river and some distance away. Here's a LINK to a Google page of the area. The rail station is in the upper middle. The B flag is Avis and the A flag is Europcar. Tim says that Europcar is in the train station but I don't see it there. I even went to the Europcar website and the address wasn't near the train station. I could be wrong. If you might be heading towards Burgundy, Dijon would be great. 2hrs out of Paris and the rental car agencies are right in the station. I believe that there are three agencies there. We have turned in a car there and it was quite convenient.
Why not just keep heading south by train and leave yourself no more than a couple of hours' drive to your final destination in Dordogne? Bergerac would be my first choice. It involves a quick train connection. It has a charming medieval center and will put you immediately in the atmosphere of the region. I have also found that the people there are used to English-speakers. Périgueux would be my second choice.
Brive-la-Gaillarde would be my third choice, only because it would be a more direct train. Having done the drive between the Dordogne and Chartres, it is very long... I would not really recommend it.
Libourne would also be a good choice - direct TGV (Bordeaux line). It would allow you to stop and visit Saint-Emillion on your way to Saint-Cyprien. Libourne has lots of decent accommodation choices and rental car outlets across from the train station.
There's a direct train from deGaulle to Angouleme that takes 3 hours, if you prefer a shorter drive to St. Cyprien. The same train also stops in Amboise and continues (with a connection) to Libourne. Whichever you decide, I think it's worth avoiding the jet-lagged shuffle across Paris with all your bags. Question: Is a flight to Toulouse feasible for you? It's a marvelous city, and well within striking distance. And you'll be at the airport anyway.