Wirelessly posted (BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
" If you're flying 1W, you can have a stopover in 1W hubs (MAD, LHR,...)"
This is not correct. If you are redeeming AAdvantage miles, you get a free stopover only at a North American gateway. If you are redeeming BA Avios, you pay for each flight flown (although an intra-U.K. segment is no additional mileage).
If you redeem for a distance-based oneworld award (as opposed to a typical one-way or roundtrip award), then you can stop over anywhere along the itinerary.