FF wise those are different as possible.

Hawaii is the most popular ff reward and all airlines have good rewards there with good availability.

Australia is one of the hardest ff rewards to get and always takes a lot of ff miles when you can get it.

I've only flown CO & UA to Australia. There are plenty of opportunities right now to get oodles of miles from Chase cards for United- besides the UA card there's Sapphire, Ink Bold, and Freedom.

Hawaiian cards from Bank of America and Bank of Hawaii are churnable every 90 days or so for 35K miles each. Hawaiian flies from California and soon New York for 35K RT coach.

Virgin Atlantic cards from Bank of America are also churnable for 50K each time and VS miles can be used on Hawaiian. In reverse, Hawaiian miles can be used on Virgin Atlantic for tickets to Australia avoiding most fuel surcharges.

By all means, you and hubby need to both get the cards to get enough miles for all you want.