If you’re up to and especially ready to pay for commercial, high-end erotic massage services then there are a few noteworthy studios to pick from in Nice. Paradis (http://paradismassage.eu/) around Promenade des Anglais, behind the Palais de la Méditerranée, has a huge menu of different therapies such as a 6 hands massage. To me that sounds like a cure for impotence but note it will cost you €450 for an hour.
In the erotic massage segment, in France usually called “massage relaxant naturiste”, there are also quite a few independent masseuse active in Nice who are adverting online. These include ladies who might also be open to more naughty services. Most masseuses will have a profile on the well-know local or national directory sites and only a few sensual massage service providers will run their own sites. There are a number of masseuses, often of Chinese origin, that offer their services to people on the beach. While their services are far away from an erotic or even a sensual massage, they know what they’re doing and posses definitely some skills. So it’s not impossible that with some ladies you could negotiate additional “techniques” in your nearby hotel.