If your railing is rotted, there are wood hardeners and fillers to use so that it can be repaired. Your contractor will tell you he can replace it and that they ARE again making the same style posts and railing. Don’t believe them. Today there is an abundance of architectural and decorating products on the market advertised as Victorian. Unfortunately, although advertised as such, these products are watered-down versions of an original or merely someone’s interpretation.
The principal difference in a reproduction architectural product (decorative molding, newel posts, railings etc.) is the size. Although only one or two inches narrower than an original, a reproduction newel post, for example, can drastically effect the appearance of an entire house causing it to lose its sense of structure and appear to be off balance.
The abundance of these new watered-down Victorian architectural elements on the market can result in fooling the public to actually believe that it is an authentic reproduction. Those with vintage houses may hastily, yet innocently, choose one of these products as an inadequate replacement for an original since it is the closest to what they have. Vintage homeowners may not recognize this error, but if you were to stop and observe the entire house, you will get a feeling of disharmony. Once your eyes are trained by comparing, you will see that the ideals of proportion and scale are missing. A millworker trained in restoration will be able to make what you need. True, it will cost you more, but you owe it to your house. The house will be a legacy to future generations long after you're gone.
Let's focus on the railing problem-
Aside from the problems of poor reproductions, there are municipal code requirements. Most codes require that a railing be at a certain height today. Years ago, as you will see in some picture examples, the railings were designed to work together with the architectural balance of the house and rise no higher than the bottom sill of the windows.
If your railing is original, it will be the correct height and style for your house. It can be temporarily removed and repaired. But if you replace it, as most contractors will suggest, it will have to meet the code which means sometimes a foot higher. This creates a "caged" effect and blocks part of your windows. Review the examples below. They are not the best. You still need to see the house in its entirety, but you will know what to look for and be able to see the difference when on your own.

This Lattice has a house attached to it!
Painting the lattice
the base color of the house
will cause your eyes to
be directed to the house,
NOT the Lattice.