My wife wants to buy a roll aboard (but not your standard "suitcase" style).

she unfortunately fly's coach more that not (especially when she is not with me). I know that the aisles in coach are tight, and when I travel with my laptop bag (Swiss Army / on wheels) which id 17" wide. it is t a tight fit to roll it down the aisle.
The one she wants is: 19" wide. Does anyone know what the coach "aisle width" is on the different AA equipment; m80, 737,757,767?
Thanks