line width adjustments

I would like to be able to change the width of a line. If I just use B/W the use of line widths and styles can differentiate a number of lines. Currently, I do this:
         p = plot(datar,-1.0*(pr),'b')
         p.extend( plot(datac,-1.0*(pc),'r--'))

Is this the way to do this? or is there something more eleganf. It might be useful for the third argument to have color, style and width.

I have not been able to figure out how to change the line thickness of the axis frame, i.e. the x and y axis themselves. There are examples for the grid, if one is used, and the tick marks but not the frame itself.

Thanks for any help.