I would start by determine what your goal is, for example destinations/airlines/class. If your goal is to travel SQ Suites for example doing an AA mileage run would be pointless.

You may also find simply buying miles when on sale cheaper and obviously less time consuming than mileage runs.

See also: http://www.flyertalk.com/forum/mileage-run-deals-372/
http://www.flyertalk.com/forum/milea...iscussion-627/