Versailles, Giverny and short Loire Valley Chateau Trip and Back to Paris

This is very ambitious, and there are several ways to do this that waste less time and are less stressful. In addition, you have four days of activities squeezed into three. Driving is not necessarily the most efficient. Trains are faster, especially to the Loire Valley.

First if you rent a car, you don’t need to go to CDG to pick up and drop a car, which wastes an hour each way. Second, Giverny doesn’t take all day. You could be on your way to the Loire in the afternoon. Third, go to Versailles on your way back from the Loire and drop your car at Orly Airport afterwards and take a taxi into Paris. The only problem is you don’t have time for the Orsay, Montmartre and a boat ride.

Alternatively, you can remain in Paris, not have to change hotels several times and do day trips. Day 1 Giverny and something in Paris in the later afternoon and evening. Day 2 fast, early TGV train to Tours and join a guided visit of some chateau for the day. Day 3 train Versaille, which is really a suburb, and evening activities in Paris. Also, in Paris, taxis have the right to use bus lanes. Ubers don’t.

mjacksonmd,
Since you asked, this does sound too ambitious to me. What time does your plane arrive at CDG and where are you coming from? Even if you arrive early in the morning, it will take some time to get through immigration,etc. And last time we picked up our reserved car at CDG, it took us a good hour (waiting in line at rental agency, paperwork, finding the car, checking it out, and getting out of the airport...not a snap...to get on the right road to our destination. Then about 1 1/2 hours drive time to Giverny. If you have been on an overnight flight for several hours you may be tired. It is recommended that you get a reserved time at Giverny, so you may have some anxiety about arriving there by the time of your reservation.
And if that does work out and you spend the night near Giverny and get started in good time the next morning, driving to the Loire Valley will take about 3 hours, so I envision you getting to, say, Chenonceau about lunchtime. You could reasonably visit two chateaux in one afternoon, but three would be rushed if you want to spend a little time at each one. (Don't forget to allow time to have lunch, make comfort stops, etc.)

If all this works out, I would not go to CDG to return the car (It really is a royal pain of an airport to navigate, IMO!) You could drop it at Orly and taxi or take a train into the city, or drop it at St. Pierre de Corps (Loire Valley) and take the train to Paris from there, or Versailles. If you get started from the Loire early enough you could drive to Versailles, return the car, and do your Versailles visit that day. Stay there overnight, and take a train into Paris the next day. Lots of options for your car return, probably with no extra cost, or very little extra. All this is up to you.

One other thing to remember...at most chateaux, the parking area is usually a good little walk to the actual chateau, and with some, the grounds are very large, so to visit them, you would be wise to allow at least two hours apiece, minimum. Likewise Versailles. It is huge ! It can easily be an all-day experience. And it requires a reserved time, as do the chateaux.
All of this assumes that you are fit and content to move at a good pace. (Unlike me and many of us here who are of a certain age!)
We each have our own travel style, and mine is slower as I get older. However, it is important to not underestimate the distances between places, the size of the sites, and the time it takes to go from place to place. (The chateaux are not next door to each other, and the ones you decide to visit may be at opposite ends of the valley. Also, you can't just drive up close to the chateaux.

The website viamichelin.com is great for planning the routes between places, and for finding scenic routes if that is your thing. Just be aware that their travel times don't allow for gas/potty/meal stops. It is very good for figuring out if your plans are doable, though.
Lastly, when are you going? The Olympics and Paralympics will have a big impact on your Paris time and expenses if you are going this summer and into September.
I hope I have answered some of your questions to help you arrange your plans. Paris is a wonderful city and France is a wonderful country! Amusez-vous bien et bonne chance!

mjacksonmd,
Bets' recommendations are good ones. I made an assumption that you were arriving at CDG. If not, then she is correct about not renting your car at CDG and getting to Giverny earlier in the day, and driving to the Loire that afternoon. Are you coming to Paris from somewhere by train? Or are you flying in from the US? Or will you already be in Paris?

And, yes your Paris plans sound too ambitious. Prioritize your Paris sights, factor in how many days or half days you have there, and go from there. You can search the forum or the RS website for opinions and info on the places to visit in Paris. Your local library will probably have some travel books you could peruse for suggestions. Have fun making your plans!

Thank you all three above!

So even though Olympics over by Sept will the first week of Sept be a bad time to be in Paris?

Paralympics is Aug 28-Sept 8.

Have you already visited the city of Paris before this trip? You don't seem to have allocated much time to one of many people's favorite city. We took the TGV to St Pierre des Corps and rented the car there. We used a local Paris train to Giverny, but I concede that it doesn't stop right at Monet's garden. Isn't Giverny the opposite direction from the Loire?