The commutability of lines on either fleet are dependent on your seniority. I would expect that a new hire won't find most of the lines commutable as more senior bidders bid them. For the 320, LGA trips tend to start earlier and finish later, although they are higher credit. So you might end up with more days off on your schedule if you bid all LGA (I would assume that is an easier commute from ATL on DL vs to EWR on UAL), but you might have to commute on some of those days off. EWR trips on the bus are more generally the flavor of start early, finish early or start late finish late, so commutable on one end or the other. You can group multiple trips into work blocks, though, where you are flying multiple trips back to back and build a commutable line that way.