Great site, stumbled across it yesterday and read your awesome info on the challenge. I've been an AA member for several years, but lost my Gold elite status two years ago when I took a local consulting gig. Now I'm travelling again on a new job, so I called AA today and signed up for the Platinum challenge.
The information on your site was correct: I did not have to do Gold first, I signed up for Platinum directly. It is still 10,000 miles, 3 months, and can start on the 1st or 16th of the month. Mileage rates they quoted me were: 0.50 for discount, 1.00 for full fare coach, and 1.50 for EITHER business or first class.
I should have my Platinum status in just over 2 months...
Thanks a lot!