We will be arriving at CDG around 10:30 and are planning to take the 12:30 train from CDG to Nice. I wonder if two hours is enough.
It might be enough. You'd want three to be safe.
It will be a lot faster and possibly less expensive to fly. You are already inside the airport. That's a 7 hour train ride with a connection to a local train in Marseille that has no reserved seats. The flight is one hour with a sensational landing out over the water with the mountains sparkling on the other side. It's a wonderful flight especially with a window seat.
That’s what we’re thinking of flying to Nice. EasyJet only has an early-morning flight on that day. Air France is quite pricey for the three of us.