Maurus
The Great Gazoo
Its fine if you have a reciprocal agreement with those regionals. Basically, no recip, no ride! CASS is irrelevant. I wouldnt say SWA is the "best" to have a recip with, it all depends on where youre at and where youre trying to go! up in Seattle, SWA isnt all that great for example.
Saying that, Us Air, Hawaiian, Jet Blue, and Virgin America will let AMF guys jumpseat (at the discretion of the flight crew of course but the gate agents will let you down to ask). From my experience, thats about it. Ive tried almost everyone else
I just find it the best since all locations are mainline no matter what. Unfortunately they don't go to every city, but at least you can get around if you need to without getting stranded because of changing airlines.