Those award flights may not be for the routes you find useful, or they may include especially expensive awards that don't make good use of your miles. (travelcodex.com)
If, however, you are on an upgrade eligible fare, this can be a very good use of miles. (creditwalk.ca)
As mentioned above, creative use of stopovers, flying routes where there is little competition or flying last minute are all good uses of miles. (creditwalk.ca)