United doesn't give free upgrades to E+ to US *G the way they do for their own customers, but sometimes the kiosk gives me a free E+ upgrade if seats are available. Does this also work for online check-in? What's the best way to maximize this? I've realized there's no way I'll get a free upgrade to business or first, but I'll certainly take more legroom (and laptop room) if I don't have to pay for it. I asked the United customer service counter about benefits, and, for domestic flights, all *G gets me is free baggage, the priority security line, and priority boarding. For international, it's that plus lounge access. Am I missing anything?