We recently mailed our passport to Consulte General of China in Chicago for renewal. It's easy and fast. This time the embassy left me a good impression.
We mailed passports, photocopies of VISA (no I-20 or I-94, it seems VISA copy is enough), filled out forms with photos, and a cashier's check (10 for each passport renewal and 5 for one package handling fee). A filled out fedex envelop was enclosed (Fedex saver, cheapest one, $9 plus).
It took only 3 days for the Consulte to process it. Thanks!
Please note that the return package was opened on its way maybe because we filled the sender and recipient the same name and information, and that might cause some doubt by Fedex and they checked it (for terrorism?). So I may like to suggest you use your name and your wife (or else) name, work and home address for the return package.
Please also note if you need to renew your passport, do it asap.
Good luck!