the oneworld tool is, frankly, rubbish. Better to get a subscription to ExpertFlyer and look there for the desired fare class (eg D for business rtw).

for the final booking many of us here use AA’s RTW desk, which can be very helpful. Sometimes they make a bit of a meal out of simple things (changing the time of a flight took 15 mins on the phone and 24 hours to reissue for example). But in general they are quite professional and knowledgeable.