How can we monitor SSL Certs in an AWS Classic Load Balancer?
Use Server and Application Monitor module. Specifically the component monitor 'SSL Certificate Expiration Date monitor':
http://www.solarwinds.com/topics/ssl-certificate-monitor
http://www.solarwinds.com/documentation/en/flarehelp/sam/content/sam-ssl-certificate-expiration-date-monitor-sw3311.htm
Also, AppInsight for IIS:
https://thwack.solarwinds.com/community/solarwinds-community/whiteboard/blog/2015/02/25/solarwinds-server-application-monitor-extends-support-to-the-cloud-adds-appinsight-for-microsoft-iis
SolarWinds Server & Application Monitor (SAM) features several powerful new enhancements and expanded application support, allowing IT pros to better maintain business-critical application performance. IT pros with heterogeneous IT environments can now monitor apps and servers on premises or in the cloud and can assess application performance as it relates to other IT infrastructure components within the new AppStack dashboard.