Scheduled to spend three nights in Amboise then drive to Paris and turn in the rental car at Gare de l'Est (by noon) so that we can take a 3 p.m. train to Munich. What are people's thoughts about this versus driving from Amboise the afternoon before and spending the night near the train station ? (With the latter scenario we would return the car to Orly to avoid driving in Paris) Rental cost would be the same for 6-1/2 days or 7 days but we don't want to pay for an additional day in case we get delayed (or lost) in the morning.
For driving in Paris, getting to the Gare de l'Est is about the easiest drive in Paris. From the Porte D'Orleans, you follow the road set out by the Romans through the city in one straight line: only the name changes as you move north LeClerc, St. Michel, cross the Seine and up the Blvd. Strasbourg which deadends at the station. It's a one-way street, all the way. The road is 3 or 4 car lanes all the way and one or two for busses, depending on which section of the route. Just stay out of the right and left lanes. The left becomes a bus lane going south, so stay out of that. Your only unknown is traffic jams, particularly on the Ave. LeClerc where some traffic merges. A Paris jam is like trying to jocky into line to get to the toll plaza on the East Bay side of the Bay Bridge, cars coming from every direction, but you eventually get through. (May have changed since I lived there.)
I'm curious as to why you are driving into Paris rather then turning in your car in Tours then taking the train to Paris and beyond. I would never attempt to drive into Paris and the train from Tours - actually St. Pierre des Corps is fast and easy. There are a number of car rental agencies right at the train station which makes it extremely easy.
I would encourage you to at least consider not driving into Paris unless you have a lot of experience driving in large European cities.
I'd go with Plan B, drive up to Orly the afternoon before, drop the car, and stay somewhere in Paris the night before your train. But you don't have to stay near Gare de l'Est in order to make a 3 pm train, just give yourself a margin of time to get there by metro or taxi from wherever you choose to stay. Driving up from Amboise the day of your train will take awhile, and you can't count on a fast trip through or around Paris to the station. Orly would be much easier to reach from the south. However, Ed may disagree, he's the original road warrior! ;)