htpp://www.nbtda.com National Bicycle Tour Directors Association
http://www.adv-cycling.org
http://www.bicycletour.com
You will be able to find a tour to fit your needs/desires/location/schedule on one of the above sites. I am a member of the NBTDA and Adventure Cycling so I listed them first :>) IMO supported tours are an excellent way to determine if you like touring.
There are so many fantastic tours it is very dificult to decide......
Good Luck and Happy Touring.