If most of your 2024/25 travel is on UA/AA, no reason to go for PM. Also being SEA based, I dropped from PM to GM and I did not have as much of a difference in upgrade % as expected, but most of my travel is now in the western half of the U.S. If doing a lot of TCONs, c+ at booking would be much more valuable. When I dropped down, I also tried to book as far out as possible, but with schedule changes and most flights that are way in the future that you would want to be on being insanely high priced, none of my seats stuck beyond March. In most cases, buying an F seat closer to departure was cheaper than buying a y seat with a free upgrade to c+ 6-12 months out.