I am surprised to see DL and CO flyers switching to AA. I was PLT on NW and had about 99% upgrade success. On AA unless you are EXP there are no complementary upgrades. Yes they have stickers but 10000 miles gives you 4 stickers. I takes 6 just to fly BOS-ORD-SNA!
Overall I do think AA is better in Y then NW but the upgrades were much easier on NW. My first complete year with AA will by 2008 so trying to make it to EXP.
The challenge is what diminishes the value of PLT. Even thought I did the challenge and got the status so does everyone else! So when they call boarding for PLT & EXP the entire plane boards - reminds of boarding on SW.