Europe with a 4 year old - please check our itinerary below and tell me if this is unhinged? lol

I’d just stay in Tuscany for the week rather than go to Cinque Terre. I think five is too young for the trails and will likely be happier elsewhere.
Otherwise, it’s more moving than I would plan for two adults, and some really long drives, but it’s far from the craziest itinerary I’ve seen posted online.
You need to sort out some details because a cross border drop off of a rental car can be pricey.

Before I answer - have you thought of using the train some? parking is not easy in some of your places.

@valadelphia - yes totally understandable. Thank you we will keep that in mind --- right now it's between Cinque Terre and Lake Como; the former is, from what I have read about, is not too accessible for strollers, etc... while Lake Como might be pricier but more chill.

@ChinaLake67 - yes we will consider the train as well. I think regarding parking, like we did in the past, is we usually just park (sometimes paid, sometimes included with our hotel/bnb) to the major city and still walk/transit within the city .

It would help to know what you want to get from the trip, what your interests are, as well as where you have already been. Three nights in Marseille is probably the thing that jumps out at me. Why? And why so many cities? By that I mean both why are you trying to pack in so many destinations in a month AND wouldn't your son prefer to spend time on a beach or in the country?
I understand you to mean that you prefer a car so you are not so limited in what you bring on the trip. But flying from Porto to Rome is only available on Wizz and RyanAir, as far as I can tell. These airlines have significant luggage limits.
You should be able to rent a carseat or booster along with the car, rather than bring one along.

Lake Como is our most frequent European destination. Stay several days(3-4).With such a young child, I would replace le Cinque Terre with
Portofino.

It would help to know what you want to get from the trip, what your interests are, as well as where you have already been. Three nights in Marseille is probably the thing that jumps out at me. Why? And why so many cities? By that I mean both why are you trying to pack in so many destinations in a month AND wouldn't your son prefer to spend time on a beach or in the country?
I understand you to mean that you prefer a car so you are not so limited in what you bring on the trip. But flying from Porto to Rome is only available on Wizz and RyanAir, as far as I can tell. These airlines have significant luggage limits.
You should be able to rent a carseat or booster along with the car, rather than bring one along.

OK. So we will be in Europe to attend some tennis tournaments and we are anchoring our trips to Madrid, Rome, and Paris. So I am looking for nearby cities to go to if they would be a short flight/drive.

Thank you for letting me know about the flight from Porto to Rome--- in that case we may look into flying from Lisbon to Rome instead- but upon checking looks like only one more airline would be available for that so we might take the extra luggage fees with RyanAir/Wizz.

Haha, I am curious about Marseille! Why do you think that? Is there nothing to do there? LOL

Thank you for your input :)

I'm sure you can find plenty to do in any city. I've never heard anything good about Marseille. It's reportedly big and dirty. There are so many places in southern France that I would visit before Marseille. Nice and all of Provence, for example.

It used to be expensive to drop a car in another country, I don't know if it still is, but if so you are doing that twice. As well, the transponders for the toll roads used to be different in Spain and Portugal, so you might want to check that. Personally, I would drop Portugal , and spend more time in Spain, you have lots of other places there you could see.

hey hey jetsettingmama
my own opinion is too much traveling especially with 4 year old. your days are so short to stay in to at least enjoy & relax especially with baby. bring a car seat and stroller. make sure car seat fits in european car. since he is older now, never know what changes will happen when you travel. make time to him to run wild, get energy out, wet feet in water.
i would do lisbon/porto another time and spend more time in spain, rome, tuscany, and preferably lake garda
pay close attention to rental car, you will need an IDP (aaa.com/IDP, mandatory in italy) use with both your DL and IDP, good for a year, pay $25/ 2 passport photos, get same day for all drivers. read up about all driving in your countries you visiting, parking, ZTL zones, if need vouchers/stickers, , automatic/stick shift, where to return cars hours/days open. many open half days saturday and closed sundays. most important pick up one country return to another will be BIG BUCKS drop off fee. many use autoeurope.com
do you have a trunk to hide luggage while traveling/stopping for safety
tuscany is a big area of florence, where are you planning on staying? drive to lyon and you could go to annecy on the lake with activities/attraction with an area on the lake for your boy to enjoy. train to paris to finish your trip.
you have a lot to think about and different places to see. you are traveling in high season with my places crowded/busy, with many others want to see the same as you. book things early. do look at train options since many are city center to city center.
good luck doing research, it gets crazy and mind boggling but that's part of the trip, once done you'll be good. keep asking questions and get more ideas. enjoy
aloha

jetsettingmama,
Your trip sounds like fun, but I have a few comments.

1. It will be very expensive to rent a car in Spain and drop it in Portugal. I would guess at least 500 euros extra. Trains between cities in Spain and Portugal seem to be not very convenient either. A flight might be better. Things may have improved since we did a Spain/Portugal trip, but recent entries on the forum indicate that flying would work better. (We flew Barcelona to Lisbon, then train to Porto, and flew Porto to Paris.) You could maybe find flights from Porto to Rome.

2. Rental car companies may have car seats available, in Iberia, Italy and France. It's worth the research so you may not need to bring one. You should definitely do three separate rentals. A drop-off fee in a different city of the same country should be minimal.
3. Cinque Terre wouldn't be a great place for a small child due to the topography. Lake Como is a better choice, IMO.
4. See #1 about drop-off fees...Fly from Italy to Marseille. There can be lots for the three of you in and around Marseille. (My husband spent some of his childhood years there and we took our kids there at 8 and 10.) You can explore Chateau d'If, visit the fishing boats in the early morning when they come in to sell their catch, at the Vieux Port, take the funicular up to Notre Dame de la Garde. (Inside are lots of model boats hanging from the ceiling, each one representing sailors lost at sea.), take a boat ride to see the calanques, have a Marseille-style pizza or pisalladierre at a restaurant in the Vallon Des Auffes where the fishing boats are tied up. And like any big city, there are lots of parks for letting off steam. You would be better off without a car in the city of Marseille. Driving there is a misery (and my husband has LOTS of experience driving in and around Marseille...he still has familiy there...plus parking will not be cheap, and he won't drive in the city if he can avoid it). Rent the car for France when you are leaving the city. Take a shuttle or bus or Bolt to the airport and get the car there. It is outside Marseille and on the way north to Lyon. Drop the car before Paris (at Orly, for instance) and take the RER or a taxi to your Paris hotel (fixed rate for up to 4 people with their luggage).
5. A toddler or small child will need more entertaining than an 18 month old. Be loose with your scheduling and prepare to make changes in daily plans. Dinners are very late in Spain and Poirtugal, so suss out your cafes, etc. for hours that fit your little one. Watch what the locals that have little ones do. I imagine the kids don't eat quite as early as they do in the US. Italy and France dine later also, but I don't think any country dines as late as they do in Spain.
6. Seek out local markets, especially in small towns or neighborhoods. You will find fun things for lunch, what-nots and playthings for your little one to keep as a souvenir, and a nice family ambience.
7. You will find many places that aren't stroller-friendly (cobblestones, steps, etc.). Large balloon-type tires would be easier on your child if riding in a small stroller.

8. Your at-home routine will probably be out the window. Tant pis! Just do your best, be flexible, pack your patience, and have a wonderful adventure!

jetsettingmama,
In spite of my advice above, I do concur that you are moving around a lot in one month. It will be tougher on you two AND on the little one with so many frequent changes. The suggestions to skip Portugal, although disappointing, is good advice. Likewise, Rome for 2 nights is just one full day. I would drop the 3 Cinque Terre or Lake Como nights and add them to Rome. That gives you 4 full days there, and there is a big variety of sights and activities for a family. Then Tuscany (whereabouts in Tuscany?), and afterward drop the car and take a train to Marseille.
As to Marseille, if you don't have a specific reason to be there (tennis matches?), the advice to go to the Riviera is wise and may be more enjoyable for all of you. Kick back at a beach, eat LOTS of great food, take buses or trains back and forth between towns (frequent and close by). Catch your breath here, then get a car and drive to Lyon and on to Paris.

Okay, now that we have all replanned your vacation, feel free to ignore our advice and do what pleases you and your family. Have fun!

If you want to visit any museums I would be very careful with a 4 yr old who wants to run around and touch everything.

On the other side young feet pus the child will be tired soon because the mentioned destinations cover huge areas. Strollers are not easy to use in cities with old and or cobblestone pavements.

For most listed cities rental cars are not a good idea plus you would have to care for driving permission (not license only), rules, special requirements like vignettes, children seats ... in every country.

As you prefer to drive, plus you have a young child, I’d recommend staying outside of cities in small towns or rural locations then just visiting some of these cities as day trips. City breaks aren’t really ideal with young kids in my opinion. Smaller places will be a lot more relaxed and it’s much easier to pick up groceries and find space to play.

Did a quick look at one way car rentals

Madrid to Porto ~$700 one way fee ( in addition to base rental cost)

Rome to Paris ~$600 one way fee ( in addition to base rental cost)

Those costs would give many cause to re-think the rental car option.
If you don't mind the cost to have the convenience 'freedom of movement' ( except when finding parking) then do it.