TGV vs. TER in South of France

I don't think the TGVs run all that fast in that part of France. You can check the running time against mileage to get an idea. I don't remember any blurring.

For some trips involving smaller towns you won't have a choice--it will have to be the TER.

On TGVs you'll have a seat reservation; on TERs you'll have to grab a seat like everyone else.

The seats on the TGV will be more comfortable, probably with extra padding, and the carriage may be less crowded. However, I never found the TERs uncomfortable.

You may sometimes find rather sharp price differences between TERs and TGVs, especially as you get closer and closer to your travel dates. If there's a change of trains involved, the extra money for a part-TGV routing may not actually save you any time.

Be alert on the trains, especially along the Riviera. Pickpockets were active there last May.

TGV or TER It seems to me both just a blur.

The scenery is not a blur on the TGV; the TGV trains are traveling at a maximum of 186 MPH for the stretch from Paris to Marseilles so from Valence to Marseille, it is a high-speed train. I have been on it and it was not blurry to me. It's sort like you see something and then it's gone as opposed to being blurry as you pass it. After Marseilles, the trains are currently not functioning as "high speed trains" in the sense that they do not travel at such high speeds because the tracks cannot handle that. The roughly 125 mile trip from Marseilles to Nice takes 2.5 hours on a direct TGV versus 2.75 on a direct TER. Can you get what you want from the trip traveling at the speed of a car going between 45 and 65 MPH?

Realizing that it is too late to change your itinerary, while the TGV is plenty fast enough on the Paris/Marseille line, if you ever want to get a splendid feeling of zipping through the French Countryside (scenery be damned!) the fastest FEELING train is the Eurostar from London. Same speed as the TGVs, but it seems lower to the ground and standing in the bar car and watching the world go by at 180+ miles per hour is a rush, literally!

But in the South, I agree that things aren't all that fast as you travel through Provence and the Cote d'Azur. Plenty comfortable.

If your seat faces "backward" to the direction of travel, you can focus for longer on a bit of countryside as it recedes away.

Take the TGV to get to the region, but once there just take whatever is most convenient.

There can be considerable price difference. TGV ticketswill be two or three times more costly on the fast trains when purchased day-of-departure rather than when sales open months in advance. TER prices are pretty much fixed. TGV is ultra-streamlined, as it has to be, while some of the TER rolling stock is ramshackle (or at least it was a few years ago; maybe it's been upgraded.) They are separate experiences and both worth it. And it is true that from Marseille eastward the high speed becomes semi-high, since the tracks haven't been modernized to accommodate 'trains a grande vitesse'.

PS: Some of the TGV stations are on the outskirts of cities (Lyon, Avignon) while usually the TER is older and downtown. Both end up in the centre of Marseille.