Welcome to FT!

I've booked CX First award seats many times with AA miles. Assuming CX hasn't sold out the F cabin, your odds of additional seats opening are pretty good, as CX is very good at releasing unsold seats in the last week before departure.

There is an active thread in the AA forum. In particular, check out recent postings from jamienbaker, who routinely uses miles and flies with his family (of 4) in F between JFK and HKG. http://www.flyertalk.com/forum/ameri...ilability.html

As noted above, AA mileage/fee prices are much lower than AsiaMiles and Avios.
If you can get AA miles (AA currently has a mileage sale where you can buy up to for 2.2 cpm), that would be the way to go.