In my experience, at least east coast, York is about it for manufacturer participation. Springfield, maybe.
Allentown has always treated me well when I've gone, but it's been several years (last time was 2016 as a senior at Penn State, much longer drive now).
If I recall, Lionel was at a show in Colorado over the winter/early spring.
Don't expect MTH to show up much to any from here on out.