The red carpet club is just to the left of the exit (escalator) for transiting passengers on UA. I've always transferred through the same place so it won't be that confusing to meet up. I thought you can bring at least 1 guest into the lounge? I've gone in with partner and they usually only check one of us in...but I guess I'd confirm.

you might check on a day pass for 1 person if you can have a guest. I've wandered around NRT coming the other way Bkk-ORD with the 3-4 hour layover. I'm still a bit confused with the new star + skypass terminal, but it seems like there are some larger common areas to hang out and socialize in the central building. Worst comes to worst you can wander toward to find a less crowded area to socialize.