Dave,
A general comment for all modeling work is to decide how much needs to be in 3d. As far as handrails go - there is no one button solution, unless you can be content with the stair tool.
Custom handrails: search the forum for "TrussMaker" and "handrail" or some similar combination. TrussMaker allows you to draw a 2d figure in various line colors, then TrussMaker will auto generate a 3d custom truss with either round or square elements in whatever size and direction you have chosen for that color of line. Counter intuitive that TrussMaker is your friend in this case, but very cool in actual use.
If your handrail is ultra simple, try the pipe special objects, or columns and beams.
Mark