You can sign all 3 of yourselves up for the UA and AA dining plans and attach various credit cards to the different accounts. One mile earned, spent or transferred will give you a fresh 18 months. Including UR transfers. Much more here http://www.flyertalk.com/forum/unite...merged-54.html, basically all of which applies to AA too.

AA's stopover rules could be useful to you if you can put Hawaii and Austrailia into one trip as you can stop over at HNL (and add 5K mile island hops if necessary) as long as you like in either direction to/from Australia/NZ.