You left off SolarWinds' Orion Network Performance Monitor. I'm reluctant to blow our own horn since I'm the product manager for Orion, but it's a very widely-used network management application that monitors network devices SNMP, Syslog, and Trap. Orion has a simple walk-up-and-use interface that includes built-in reports and alerts. Orion scales to very large environments but is priced for accessibility for mid-sized and smaller businesses. Apologies for the blatant plug.