Travel from nice to Portugal by train

My first suggestion is you also consider how long that train ride would be...

A quick look at Rome2Rio suggests that taking a train (comfort unspecified) might take about 32 hours.
Thirty two hours. On trains. Potentially five transfers.

A nonstop flight (admittedly, probably less comfortable) would take about 2.5 hours.

I like comfort, too, but in this case, I'd definitely fly.

Worth noting: Portugal is not well connected to other countries by rail.
Even just going between Portugal and nearby Spain by rail is not easy/quick/convenient/ideal.

Yes, this is not a good idea as there are very poor rail connections between Spain and Portugal. I would fly.

Krystal,
Are you planning to stay at various destinations along the way or do you want to travel directly from Nice to Lisbon?

If you plan to stop along the way, how many days do you plan for this journey?

If just wanting to get from Nice to Lisbon, I’d suggest flying.

You may check for flights from Nice (or Marseille) to Lisbon here: skyscanner.com

Enjoy your trip!

Traveling 1120 miles on a train is excessive. Especially when you can fly it in two hours on EasyJet--cheap.

I always try to travel by train, saving air as a last resort.

But in this case, if this is a straight through journey, air is the sensible option. There are only 2 routes- via Madrid and Badajoz, or down to the very bottom of Spain and into the Algarve. There is a third route via Hendaye (not shown on Rome to Rio) but that also needs 2 overnights.
If you took the Badajoz route you would arrive into Madrid at midnight and leave again at 8am. You would be sensible to break this journey at Barcelona- from there Lisbon is POSSIBLE in a very long day but I would break again at Madrid.
On the Algarve route you would need 2 overnight stops in Spain then the International bus from Spain to the Algarve for a 2 train day long journey to Lisbon.
Apart from possibly the first Portugese train comfort levels are high.
This web page gives details of the Badajoz and northern Spain routes (albeit from London but the principle is the same).
https://www.seat61.com/Portugal.htm
There used to be a wonderful overnight hotel train from Hendaye and also from Madrid but that vanished in Covid.
So it only makes sense as an overland adventure, not as a straight point to point. Air would also be vastly cheaper.

This journey is a bit like me planning a journey from the UK to Seattle. My heart would just love to fly in to the East Coast then Amtrak across the country on a through journey, no stop overs. Last time I came to Seattle I flew into Halifax NS then Via Rail/Amtrak Cascades via Toronto and Vancouver BC as part of a much longer journey. My wallet says fly all the way as it's vastly cheaper, and my common sense says that the Amtrak route is wasting time I could be in the PNW.

Yes, thank you… train travel doesn’t make sense in this case with so many transfers and Lisbon not being well connected by rail as was pointed out. Before planning on flying… wonder if a two-three day route by car is feasible? Any thoughts?

You can get an estimated driving time (with no breaks, navigational errors or traffic tie-ups) from www.viamichelin.com. However, renting a car in Nice and dropping it in Portugal would almost certainly come with an exorbitant international drop charge--probably somewhere between many hundreds of dollars and a thousand or so. The French car couldn't be rented out in Portugal. It would have to be fetched and transported back to France.

Besides the rental drop-off fee, the distance is considerable and 2-3 days is not enough to make a real road trip out of it. You would pass by many highlights, each worthy of several days! Plus, gas and French tolls would cost a lot more than 2 plane tickets, even without the rental cost.

Yes, I can confirm driving rental car is expensive with tax in excess of 1,000! If we are determined to visit those two destinations I can see flying between the cities is the best way to go. Thanks for all your input:)