It has gotten to the point where US is offering better service than UA. And I never thought I'd come to say that. My last flight on US, BUF-LGA-DCA, I arrived at the gate in BUF to my name being called. Figuring this is NEVER good when one doesn't have an upgrade pending, I wasn't surprised when they told me BUF was going to push about 45 minutes late, which called my 60 minute connection at LGA into question. Steeling myself for a night in Buffalo, the friendly agent asked if I'd like a boarding pass for the non-stop BUF-DCA flight (which had been full at the time I booked) as an exit row seat had come available? Or did I want to take a shot on my ticketed flight?
A quiet (albeit slightly delayed due to weather) nonstop later, and I got home 90 minutes earlier than scheduled.
I can't recall the last time UA proactively offered me a re-route based on the mere potential of a mis-connect. It was a simple, costless step by US but now has me viewing US as a viable 1st option again -- something I'd written off in the years after their last merger.