I did this several years back, and found it to be a fairly painless procedure. You can enter immigration through the line for US citizens and permanent residents. I just handed over my documents and they directed me to a nearby room where I waited with a bunch of other people for around an hour or so while they processed the paperwork and whatnot.

Make sure your connection is not too close, as I could easily see a missed flight happening, especially if there are any questions they have for your wife. This shouldn't be the case though.

I was told to expect my green card in about 9 months, but it showed up in about 3, so I was very pleased