Good advice, especially if you can upgrade all 4 mileage runs. Remember that you AA upgrades (VIP's and miles) cannot be used for many non-AA sectors and a RTW in Y is going include some sectors that are not operated by AA, so you will be in the back of the bus for those sectors.

RTW's are great for maintaining status in most OW programs when flown in D and A, but the coach RTW is discount Y class so you get greatly reduced status earning benefits in most programs. A single RTW in A or D, carefully sculptured, can easily retain elite status in most programs, in M (discount Y) you are going to need to really max out the miles (and hours of your bum in a coach seat) to get there.