I will be traveling to the United States soon with my wife and children (less than 5 years of age). My wife is not a U.S. citizen, but my children and I are.
How should we approach the immigration officer at the point of entry: individually or together as a family?
If you are travelling together, I suggest always staying together as a family. Hand the immigration officer all your passports, and he or she will probably ask "Are you a family?" before opening them. Say yes of course, and they should have no problem processing you all together.
Since you are a US citizen, you and your family can use the line for US citizens. I have always done this (my wife is American and I am not), and have never had a problem. In fact, the one time we tried it the other way we were told to go use the US citizen line instead.
Just approach as a group.
My family (same basic composition) and I flew into Atlanta a couple of months back. We were directed to the APC machines. Those of us that had US passports put our data page on the scanner, my wife put her B1/B2 visa on the scanner.
Of course we got the big X on our slips and had to get in the line, but it was quick, a few questions about what we are doing, how long and we were on our way.
If it is your wife's first time to use a visa, you may get some more questioning, as my wife did the very first time.
But this is if your wife has a B1/B2 visa. If she is traveling on an ESTA or Visa Waiver, then procedures maybe different. Though you should still approach as a family.
The rule is that family members (especially if residing at the same address) can be processed together, so you should go together in the US citizens queue.
At most major airports, this will mean using an APC kiosk, which can also be used by VWP nationals, and at the very most major airports also by B visa holders.
