The Riviera has an adequate bus and train service and most towns and villages also have taxis.
If you intend to do a lot of sightseeing then renting a car is a great option. Be warned however that driving in this region can be dangerous and difficult as there are many steep, winding mountain roads to contend with. If you are driving, take care on these roads and travel at a slower speed than usual.
Driving a car on the Riviera is only for the brave, the region has one of the worst accident records in France and every local has his or her favourite story about a mad driver. At vacation times the driving situation is exacerbated by the hordes of tourists from different countries who have completely different driving styles. The primary artery is the A8 Autoroute which stretches from the Italian border (there is an Italian Autostrada the other side) to Aix/Marseille. If you are not bringing your own car or car seat, remember to pre book a car seat well in advance to ensure availability.
There is one main train line from Italy via Monaco/Nice/Cannes which then off towards Marseille. However, there is no train to St. Tropez. In addition to the mainline there are two scenic branch lines – from Nice to Cuneo and Nice to Digne.
If you must visit Cannes during the Film Festival or Monaco during the Grand Prix, then it is strongly advised to take the train from some station a little distance away. The train gets you into the middle of the action and you don’t have to find a parking space or battle with 50,000 other people trying to get down the limited access routes.
There is no unified bus network. Rather there is a hodgepodge of routes and information can be hard to come by on the internet. If you decide to travel by bus, ask for information at your hotel or local tourist information office for details on timetables and distances. Buses are stroller accessible and you should be able to wheel one onto the bus without difficulty unless the service is particularly busy.