They will be littered with mystery lovers who are just hanging out, looking for other people to eat with, or spontaneously creating their own entertainment. Most mystery magazines list upcoming conventions. The Internet is a great resource for this information, also. My favorite general purpose mystery-related web site is the ClueLass Web Page maintained by the wonderful Kate Derie. This web page has a lot of great information and keeps a running list of upcoming mystery conventions all over the country.
All authors are desperate to find someone who has read their books.
All authors are thrilled if you read their book and actually liked it. Most authors want feedback, but stick with what you liked. Authors are as afraid of you as you are of them. No one expects you to recognize, or have read, every author here.