We will be in Nice for a few days and want to go to St. Tropez and then to Paris. I think we can take a train from Nice to St. Tropez. Is there a train or plane from St. Tropez to Paris or do we need to go back to Nice? We have previously thought of driving but discarded that idea, Thanks.
I don't think the connections to St Tropez are as numerous as you may think. There are no flights from St Tropez. The nearest is in Nice. There are no direct trains to or from St Tropez. The closest train station is, I believe, in St Raphael Valescure. You would need a bus, or car or car/driver to get between these 2 points.
Because it doesn't have rail service, St-Tropez is particularly inconvenient to reach by comparison to nearly all the other coastal towns. I'd try to find an equally-interesting alternative with a train station. I've never bothered with St-Tropez myself, so I cannot suggest an appropriate substitute.
There are 2x daily boats from St Raphael to St Tropez (at 9:30 and 14:30) until 9th October and on 28-29-30th October, taking 1 hour. Return at 10:30 and 17:30.
St Raphael has a train station with direct trains both from Nice and to Paris, access from Nice is easy.
That's the best way to go.
If your trip is later than 9th Oct, I would suggest that you go to Cassis instead of St Tropez. It is very cute as well (smaller though), and the scenery around it is far more impressive, with the option of boat tours to the Calanques. 2 nights are usually enough. Cassis has a train station a little bit out of town, but taxis & (in season) a bus shuttle are available. You would have to change trains in Toulon coming from Nice, and in Marseille going to Paris, but that's not difficult.