I've had mosquito trouble in Nice but not in Arles or in Nimes -- seems to be one of those ~your mileage may vary~ issues.
Nimes rubbed me the right way, even better than Arles or Avignon. Dinner spots were convivial, non-touristy, good for aficionados (and showing some interesting influences, since as mentioned above it is technically in the next province westward, so some ingredients are sourced not from the Cotes du Rhone alone but also from regions leaning Basque-ward or even Catalunyan)
One of the RS-recommended hotels in Nimes has a couple who manage the place who are as friendly as it's possible to be without actually being close friends -- I'm within the solo traveler profile so it was almost becoming a boundary issue for me when they wanted me to go out for dinner with them when business wasn't occupying their time, or wanted to share an after-hours microbrew beer when the lounge was already closed. Very, very sociable! OTOH, when they were busy, they were busy.
This is them: http://www.hoteldestuileries.com/#hotel-des-tuileries-nimes-france
Note also that the sightseeing in Nimes really brings together the entire regional history, both Roman and medieval.