nice post, ngateguy.
in NH at least, riding on sidewalks is governed by town ordinance; it's illegal everywhere i have lived. i have no desire to jockey for room with pedestrians, baby carriages, older people, and children while trying to both avoid being knocked off a four inch curb and maintain a 15-20 mph rate of speed.
bicycles are vehicles. they belong on the road.
this is also, by the way, my issue with segways. a wheeled vehicle moving 20 miles an hour DOES NOT belong on the sidewalk.