B' Spokes: At the risk of influencing your answer, when I returned to Baltimore I saw a lot of "Bikes Share the Road" signs, I'm not sure if I am all that happy with that message. If I had a choice of being on a nicer car friendly road (a.k.a. Bike Friendly) where this sign was not needed, I would be there, otherwise I want a sign that says something along the lines "Motorist, please stay on your designated motorway known as interstates. We paid a lot of money for those so please use them but if you must use other roads please remember when not using the interstates you are on PUBLIC roads where all members of the public have a right-of-way whether they are in a motor vehicle or not, they are not your roads exclusively, so act accordingly and yield to others."
OK that is a bit wordy and would never fit on a sign, so that's what was nice about the "Share The Road" campaign... it fit on a sign but without a lot of public awareness efforts it does not often translate to anything close to my long version.
Survey from Bike Maryland at: <a href="http://www.surveymonkey.com/s/GTZVBM9">http://www.surveymonkey.com/s/GTZVBM9</a>