Legality is usually determined by a local ordinance, so everyone is going to be different. Your state may allow it, but a local ordinance may prohibit it. Pretty confusing.

It is a bit easier in Europe, where countries like Germany prohibit all riding on the sidewalk (unless you are under a certain age) and at the same time provide a wonderful cycling infrastructure.

I ride on the sidewalks sometime but usually try to keep my speeds from 10-13mph (and give audible warnings to pedestrians). Most people can accept that.

I tend to ride 20+ on the street (solo, faster in a pack), and those types of speeds on a sidewalk seem to frighten and/or anger just about everyone (pedestrians and autos included).