One more thing about the lounges - United's lounge will be closer to your gate if you're flying United. So that might be the best place to rendezvous with your wife.

Depending on what your wife wants to shop for, she may find the shops before security quite interesting. There are lots of stores selling souvenirs, Japanese delicacies and so on. If she's looking for brand goods, after security is where it's at (although, I'm told that the prices for such things are better elsewhere).

With so much time before your flight, you might like to visit Narita City. I think I'd prefer that to killing five hours in the lounge. After checking in for your flight, head down to the station and jump on the local Keisei train.