Relax. Rest assured that no one at the airport will ask any itinerary documents or other information from your wife. Once you both explain that you both live an work in the land of down under and are now just coming for vacation, and have the return tickets to prove it, she'll have no problem to be admitted. They will not give her any hard time at the airport, for even the dumbest CBP inspector will see that see is the spouse of a USC and that she can apply for and obtain a green card anytime. Welcome home!
Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
Take evidence of your job(s) in Australia and return ticket home. I agree it should be fine.
Due to the nature of this forum, Attorney Maria J. Marty does not have all the information required to provide legal advice. Accordingly, her responses on Avvo are intended as general and not legal advice.
She should have a nonrefundable return trip ticket and evidence of her residence and employment in Australia.
Mr. Shusterman's (former INS Trial Attorney, 1976-82) response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.