I'd appreciate ideas on how best to find contact information on missing classmates. Is there a particular website or service that you have found helpful without getting sucked into something you don't want?

Check out genealogybank.com. You pay a subscription to see actual scanned pages from selected newspapers around the U.S. You can see the list of papers they scan and the years covered --- see if your hometown paper is included. Names are highlighted in yellow on the newspaper page. Lots of obituaries and you also have access to the Social Security Death Index. Invaluable for locating classmates through the obituaries of their parents, and for locating married females through their wedding announcements.

Free sites I've had good luck with include intelius.com, radaris.com, peoplesmart.com, nuwber.com, and whitepages.com --- you have to pay to get all the details, but there's almost always enough free stuff displayed to satisfy the search objective.

Facebook is also a good way to find folks.

Will also share how I found a large # of my 'missing':

I'm a 1973 graduate. I sent a listing of my missing '73 classmates to folks who organize the reunions for the years 1970-72. I was able to shorten my list by dozens of names -- as a lot of the '70, '71 and '72 classmates were siblings, cousins, spouses, neighbors, etc of my missing '73 classmates.