I googled both Bachmann and Kato snap together systems. When I googled for both Bachmann and Kato pictures it showed side by side images of track and its ballast. It also showed Fleishmann and Tomix systems, however their rails appeared smaller so I was afraid my cheapy engine flanges would be riding the ties than rails. Asked wife, Kato or Bachmann? and she liked Kato and thought Bachmann looked too big and clunky.
I mocked up an N gauge coal car with some seated O gauge figures and set it on a rail section in carnival area with an O gauge car behind it, and everything looked believable "good e'nuff".
Next step was to create paper cutouts of Kato's 11" radius 180* curves (next size up would not fit space without O gauge "surgery") and fit it into given space to determine straight pieces needed. If I used the Kato expander straight pieces I can maximize the N layout to fit.
So thanks for advice.