Many people have trouble with the size of their Temporary Dimension size being extremely small. In the last "build" (or service pack as they are now referring to them) for Revit, it noted that you can now change the size of the temporary dimensions in the reivt.ini file.
Check out the Autodesk support solution - ID: TS1074426 at http://usa.autodesk.com/adsk/servlet/ps/item?siteID=123112&id=10024530&linkID=9243099 for instructions on how to add the Graphics information to your revit.ini file.
This works great...even for presenting Revit to a group. Take a look at the image below...just doubling the default value (8 to 16) makes a big difference.
One thing to note...you have to install the latest build of Revit before this will work.