Trip Plans to France

What is best depends on a number of factors:

Will you be alone or part of a couple or a group?

What are the major interests of the travel party--architecture, history, art, scenery, food, wine, etc.?

What time of year is the trip?

Are there significant budget constraints?

Do you (because of cost or flight availability) have to fly in and out of Paris, or can you get a multi-city flight into a different city and home from Paris, or vice versa?

For 4 days in Paris you will need 5 nights in that city. Does that time include your theoretical day-trip, or is the day-trip an additional day based in Paris?

Do you mean you are considering one of these three regions in addition to Paris?

1. Normandy
2. Alsace
3. Alps

Or does one of your trip ideas have two of those regions in addition to Paris?

Acraven has given you some excellent questions for being able to help you a little better with your considerations.

I guess I would also ask if you have a strong preference for or against large cities, villages, and/or countryside.

Kim I mean in addition

I'd go with Normandy - D-Day sights, 1066 sights, Mont St. Michele.

Normandy has a lot going for it. I'm something of a WW2 buff, so there is a lot for me in Normandy. On our two trips, we have stayed in Bayeux.

After a few days there, you could take the train from Bayeux to Saint-Malo for some delicious down time. I say this because Saint-Malo and environs have some great sites, but not the "blockbuster" sites of Paris and Normandy. And, it's an easy train ride back to Paris, or at least it was in September 2019.

Again: Time of year? That would matter to me. Normandy is cooler and wetter than most of France in mid-summer, making it an especially attractive area at that time of year, when some other areas may be extremely hot.

I've visited both Normandy and Alsace without a car. It takes a bit more time to get around by train, bus or a combination thereof, but there will be plenty of attractive, accessible options for the time you'll have in either of those areas. However, I highly, highly recommend a one-day (or longer) small-group tour of D-Day sites if interest in the invasion is one of the reasons you're considering Normandy. Many of the invasion sites are awkward or impossible to reach by public transportation, and in many cases you would find comparatively little explanatory material posted at the site. A guide is invaluable at such spots, and the guide will move you efficiently from place to place, so you'll see a lot more than you would even if you had your own car.

I think Bayeux is by far the best base for folks interested in the Normandy invasion who don't intend to rent a car. It's the origin point for most of the D-Day tours, and it has multiple key sights of its own (the tapestry, the cathedral, the historic district, the Invasion Museum).

You can take acraven's word as gospel on this subject. I highly recommend Overlord for affordable small-group tours of D-Day sites.

https://www.overlordtour.com/

If by 4 days in Paris you mean 4 nights and also a day trip -- just not enough. I would split your time in half 6 nights in Paris which is 5 days and use one for a trip to Versailles or Reims or other day trip and then do 6 nights in a region other than Paris. Normandy is good but not easy to do without a car -- if you do plan to do it without a car then book a tour of the beaches (we used Overlord but there are many options). We have also visited Brittany -- St. Malo with day trips by bus and the Neolithic sites of Carnac with a guide and did a 5 night side trip from Paris without a car. Here is some of that trip to give you some ideas: lots and lots of pictures to give you inspiration:
https://janettravels.wordpress.com/category/brittany/
We did have a car when we visited St. Michel, and Etretat and Honfleur:
https://janettravels.wordpress.com/category/normandy/
There are other great regions e.g. Alsace, or Provence or the Riviera -- pick one and take time to enjoy it.

I would also recommend starting in the region and finishing in Paris so you don't waste your penultimate day rushing back to Paris for your flight.

For me, I would suggest heading down to Lyon and then to Provence/Avignon.

You can do all that easily by train and there is lots to see.

As others have said, it depends on what you want to see. Cities or country, do you like great food? ruins?

Need more than four days in Paris.

Normandy is wonderful, don't miss Bayeux and the amazing Bayeux Tapestry.

Strasbourg is great, also Burgundy and Provence. Many places on the Rhone river from Lyon south, including Aix, Eze, Avignon, Arles, and of course Monaco, Nice, Cannes, St. Paul de Venice and more.

You should reconsider the option of renting a car to travel to either Normandy, Alsace or the Alps. I've driven in all three as well as Paris. You will have much more flexibility with a car outside of Paris and it's not difficult to drive - just don't speed (they'll get you with electronic ticketing if you're not careful). You won't need a car in Paris so I would rent at CDG and then head out. Each area outside of Paris is different and you can't go wrong with any of the three. Enjoy researching and have a fun trip!

And two nights gives you one day. Tour companies try to pretend it give you three but the arrival and departure days are pretty useless. So 6 nights in Paris gives you 5 full days -- and arrival day may give you a little time, but departure day is a total waste. And apply that to moving around as well -- you lose a half day at least and sometimes a day when you change regions.

A nice day trip out of Paris would be Chartres, which has a truly wonderful cathedral and an old town area to visit. It's about a 45 minute train ride, Covid restrictions notwithstanding.

In the Alsace we really enjoy Colmar. If you don't mind the slightly touristy atmosphere it's a great place to walk around, and there are several small town nearby that are well worth the visit.

In Normandy, St Malo, Dinan, and Mont St Michel are delightful.

It's also about a 30 minute train ride to Strasborg, which also has a wonderful cathedral.

In Paris, I recommend you not miss the Paris Opera.