If anyone is interested, you can already book the night train Paris - Berlin from European Sleeper, starting March 26.
On the second day, Verona to the South of France I started with a quick 1h13m ride with Frecciarossa between Verona Porta Nuova and Milano Centrale. It was coming from Venice, so a 10-minute delay was somehow understandable, while having multiple bookings on the same seat wasn't, but the train was pretty empty, so it wasn't a headache. In Italy, take an hour between trains because it's a rare event to have them on time. The next train was from Milano Centrale to Ventimiglia at the French border and the trip took 3h44m with a regular InterCity. For the French train, I buy the tickets right before boarding because the price doesn't fluctuate, being a regular TER, and I prefer to hop on at a convenient time. From here, it takes a few minutes to get to Menton, as in my previous example, but you can get to Monte Carlo, Nice, Antibes and Cannes, among many other places. The longest ride, for a little over two hours, is to Grasse, also known as the World's Capital of Perfume, which I highly recommend at least for a day trip. #trainstr View quoted note →
SNCF has a nice Flash Sale for TGV INOUI until December 4. You can buy tickets for €19 from Paris to Marseille, Avignon and a few other destinations, with travel dates from January 6 to February 5. I took a peek and it looks like there's a lot of availability, sometimes even cheaper.