Welcome to the oneworld board
I've planned (as opposed to done!) many runs that would requalify for AA Plat based on Economy on a 4 continent OWE. I find it's not too hard to get around 60,000 miles off a ticket (qualifying via Q-miles rather than Q-points).
I'd post a few examples here but they all originate in Australia. But then again, Australia is one hell of a cheap place to start. This ticket would only cost about US$1300 - a very cheap path to Plat. My spreadsheet that calculates the route distance, bonuses and all that tells me of a cost per mile of well under 2c per mile (it even says whether posting to QF or AA is better). Email me if you want any of these suggested paths - but it shouldn't be too hard to get something equivalent yourself.