Last year, my spouse and I (we're Yanks) and I went to vacation in Spain from which I was to continue to Asia. She travelled on an F award ticket and I was on a RTW One World A ticket. However, a domestic flight from BCN-Seville wasn't covered by her award ticket and we bought a one way coach. At check-in, we inquired about upgrading her and they wanted 4X her coach ticket (not smart because there were only two pax in First). I offered her the first ticket, but she, seemingly sincerely, turned it down. Another time, in the states, the two of us with two children (one a lap seat) were together and offered one opup. My wife took the upgrade with the lap child and my son and I sat in the back.