If you have children, likely your doctor did not let her fly when pregnant, and you likely waited at the very least for 12-18 months before you dared to send your child on that 15 hour trans-continental flight, per doctor's order and courtesy for the other passengers. So, her family has not seen your child in-person ever and have not seen your wife in at least 2 years, likely more.
Your child will be a superstar in china, especially in the smaller cities and the villages. Because of this, my wife insisted on having a baby leash for him for use in China only due to the perceived high amount of baby-nappings there. My son loved the amount of people and wanted to go outside every day just to people watch from the safety of his stroller. He liked being a celebrity, I guess! :-)
She will need to take a large suitcase for gifts for her family and friends, and may bring that suitcase back full with new Chinese clothes for her and your children and possibly some gifts too.
Well, of course you have to buy plane tickets, but what does she need and what will your kids need? Your child, like you, can get a 2 year visa with a 60 day maximum stay (unlike the standard 30 day maximum stay), but you will need to send a copy of his or her birth certificate, your birth certificate, her birth certificate and passport, and your marriage license. along with your child's passport and passport photos and the proper forms. Starting in 2012, you need to use an agency or visit the proper Chinese consulate. Before Washington D.C. could handle all of them, but no more. See the Chinese Embassy web site for more information.
As for her, she will need her passport and her green card, or her work authorization card with travel authorization if she has not gotten her green card yet. That being said, I highly advise that you wait until she gets her green card. There have been stories of ladies traveling on the work authorization card with travel permit and not being allowed back in to America!
Unfortunately inflation has hit China badly and so she actually will need a lot of money. Besides her ticket, you should expect to send her with $3,000.00-$6,000.00 per month she will stay in order for her to fulfill all her filial responsibilities with her friends and families, besides the thousands of dollars she will spend on American gifts to take back to her family.
She likely will want to go for 1-2 months. There are 2 trains of thought on this. My wife went back for 1 month and after that month she was ready to come back home. A friend of mine sent his wife, who wanted to go back for 1 month, back for 2 months. After 1 month, she was ready to come back, which is the usual experience. But after 2 months, she hated being in China. She wanted to be back in her home in America. After 1 month, it seems that many Chinese-Americans realize how Americanized they have become and understand that China is no longer home to them, and that America is. However, your mileage may vary.
Regardless, to save you an average of $5.00 fees from your bank and from the foreign bank for her to take money out of your bank account, make sure you set up a Bank of America Tiered Interest Checking account and only withdraw money in China from Chinese Construction Bank ATMs (often they have multiple ATMs in front of the banks, but only one works for international cards, unknown to the bank officials, so if at first an ATM does not succeed, try, try again by going to the next machine and the next one. CCBs are in almost every city, so it should be easy to find, even if your taxi driver thinks only Bank of China can do international business!
While she is gone, enjoy your time, doing all the things she does not like, such as eating American fast food, staying up late, and not immediately cleaning up after yourself, but once she returns, have a perfectly cleaned house and gifts for her too. She will be ready to be back home and you will be ready for her and your children to be back too. Enjoy!