I would concur with Bidkat's comments concerning HP. I switched to them from UA out of DEN and frequently fly to California, including SNA, and have been very happy. My upgrade rate has been in the range of 75% over the past two to three years, and I am only Silver. HP's FC product to the east coast is comparable to UA or CO, and perhaps even a bit better than NW.

My only gripe with HP is that the steerage cabin in certain planes can be a bit cramped, especially when compared with MRTC on AA.

Yes, you will hear naysayers when HP comes up, but their comments are out of date. I think you will be pleasantly surprised by moving from DL to HP.