Intermapper works great for us, handles dependancies, has configurable timers for flapping, and all the usual + traps. Remote Access is nice, engineers can bring it up from anywhere on their screen with full maps displayed rather than just a list of probes. It's cheap. For logging Splunk works well.
We've looked at free options but nothing seems to do the job without a ton of scripting and multiple packages.
What we don't like is the cost of Intermapper Flows � ideally we'd like to have NetFlow monitoring on everything, but at $300 USD per router + maintenance, it's hard to justify. If anyone knows of decent NetFlow analysers that are less costly for 200+ routers, I'd like to hear about them.