My recent trip to France was a very last minute plan. The opportunity came up 3 days beforehand and I decided to go for it. When you cut out travelling time, I really only had two days to explore, so one day went to Nice, the other on a day trip to Monaco.
With the short time frame in mind, I centred my exploring in Nice around the old town, or Vieux Nice. This is where most of the things I wanted to see and do were, and it’s compact enough that it could all be covered in a day. This really is a great city to visit, with friendly locals, stunning views, and plenty to see and do.