Only UAL calls 737's guppies. I'm not sure why. The -500 looks like one, but the other 200 planes don't. I had a little A319 call my -900ER a guppy in SFO. If a -900 is a guppy, so is the 757. Same airframe. Same seats.

747's: you can try to keep them, but as part of the original discussion, I don't think they will survive the merger long-term. CAL parked theirs, along with anything that is old or has more than two engines. Its a money thing. I don't like the CAL way of marketing airframes and routes, but I have no say in the matter. CAL always has the smallest airframe in any given market, but they do make money, so what more can I say?