If you're looking for some simple aids to scaling, try the following two links:

http://www.sharecg.com/v/40765/view/11/Poser/Poser-height-measuring-rulers

http://www.sharecg.com/v/41322/view/11/Poser/Poser-dial-driven-measuring-tools

These are measures for use in Poser and DAZ Studio, and are also designed to be suitable for import into a modelling program to help in scaling your models.

When modelling they need no textures; you can see the numbers on the scale of the rulers in wireframe mode.  Read the ReadMe files though or you may miss some of the pitfalls, like the problem that occurrs if you forget to switch off scaling when importing into your modelling program.

I use the same 1 unit=8 feet (96 inches) as I believe it's the best one to use.  It's the most commonly used, as most modellers have ignored the scale changes since that scale was announced.