Yes, we do highly recommend vaccinating for Marek's Disease due to it being highly contagious between poultry and wild birds, as well as being spread from one contaminated area to another; even visitors to your coop can bring in disease directly to your birds. Vaccination is not a substitute for effective bio-security and sanitation practices; while bio-security still vital to practice. A single vaccination confers lifelong immunity, but is not 100% infallible. About 5% of the chickens vaccinated can still get the disease anyway. It is a good idea to have them vaccinated as it helps build up their antibodies to the disease.
We understand if you would like to raise your birds organically and depending on your state's consideration of Organic, chicks that are vaccinated within the first 2 days of life are still considered organic per page 21 of http://apps.ams.usda.gov/organic/201/Organic201-Aug2012.pdf and there are approved vaccines that are allowed under the USDA organic standards. However, it is always best to check with your certification agency before requesting Vaccination if you plan to raise them organically.