I'm looking at this as well. This year was my first when I hit the SE threshold, and I should top out around 125K.
Needless to say, I'm pleased I didn't do that MR LAX-HNL-LAX someone had suggested as a cheap way to do YYZ-LAX and get extran points back when I didn't think I'd make it. And I'm glad I cashed in points to go to VIE rather than paying to try to make SE. Obviously this would have been a waste because I made it under the original threshold, but even moreso if I had done it to get to 100K and then they lowered them. bah.
For those of us who fly predominantly transborder, has anyone else considered/decided on best option? One thing I'm not clear on with UA is if they will bump you up right away if you hit one of their elite levels during the year, or if it is for the next year only.
I'm someone who sometimes gets the cheap fares, but more often than not ends up on Y/M type levels due to last minute changes. On UA, this provides an automatic bump to F if there is space and you are an elite. On AC, it seems I would still be able to use more certificates than most.
So I'm fence-sitting right now. Would be interested in hearing from other transborder types as to where they are at. One obvious reason to at least keep AC Elite is the RCC access that the UA guys don't get.
Simon