Hard question to answer. Sketchup does great things but everything you have to show has to be made individually.
Chief has automatic banisters and newels that you can change but I think is not as easy to make as they are in Sketchup.
Doing flared and rounded stairs in Chief can be done but I think they would lack precision.
You should check out Stairdesigner at
http://boole.club.fr/english/stairdesigner_eng.php
It is a stair specific software and I think it is about $1.1k.
They have a demo you can download.
Andy.