The second part of my Nice trip has been amazing for views so I hope you'll enjoy.
The landmark we wanted to visit the most is Nice Castle Hill. It is by the sea line, south of the Old town. It is easily accessible and walkable. Since it is a hill you can get there by lift (there is entrance for that) or by stairs. I would recommend going up by lift and down by the stairs.
From the top there are many viewpoints to take alluring photos of Nice. Most of the best viewing points are marked on the map. So you won't miss enjoyable views of this pearl of the French Reviera.
Speaking about going to the Castle Hill, you might want to consider going on a full stomach since there are not many places to eat around and the whole trip can take a while since there is much to do and to see from it.