HOW TO LOCATE SOMEONE IF I HAVE NO CONTACT INFORMATION WHERE THAT PERSON MAY BE?

I had an old friend (Dennis S.) who (I heard) was killed in the Viet Nam War during the late 1960's. The family lived next door to me and my parents in the mid-1960's. I have many photographs I would like to give anyone in his family if I can find someone. I have tried locating them using our local library with no success. I don't have the knowledge of using Facebook, Tweeter to locate people. I'm in my late 60's now and I would appreciate anyone's help in locating a relative that may still be living (Dennis sister Vicky). I don't want to give any last names of the family in respect of their privacy. I am requesting help with ideas that would help me locate them myself. I will say: I believe they were from Kansas, they moved to Huntsville, AL in the mid- 1960's and I believe the father (Wayne S.) worked as a draftsman for Boeing and the mother (Millie) was a homemaker. The family moved to Florida in the late 1960's, The only family member who may still be living would be Dennis's sister Vicky. She would be in her mid to early sixties by now and I do not have a married name for her if she is married. I have about given up on reuniting these pictures with her. Perhaps someone may have an idea I haven't thought about I truly hope so and appreciate your help.