Based on Boeing757/767's list, here's some of the long distance differentiators that you can find in most photos:
737-200, -300, -400, -500, -700 and -800.
73s have a distinctive extension of the vertical stabilizer that extends well forward of the base of the fin and engine pods are flattened on the bottom.
Boeing 757-200, 757-300
75s can be confused with 76s from some angles, but in profile it is simple- 75s are the only transport of this size and configuration that have the 'point' of the nose closer to the bottom than the top, giving the nose the profile of a shark or a snake. Other similar AC have the 'point' in the middle of the nose.
Boeing 767-300 (Delta, and maybe the -200 as well?).
Easy to confuse with 77 or A300 until you get used to them, but it doesn't sound like the 77 or 300 show up at LGA- The way I differentiate the 76 is the big pointed tail cone.
Airbus A319, A320, A321-
Very much like a 73, but engine pods are round and they have the distinctive airbus 'triangle' winglets.