For network monitoring, you guys can also check out Observium, it is a lot better than Cacti + some other tools. Though it is mostly for graphing and alerts regarding the network, but what makes it much better than Cacti, is like Solarwinds, it also automate the setting up of adding devices, adding graphs and doing most of the manual work for you.
Lastly, it is open source so at least you can run it without it costing you extra monies.
+1
Zabbix is also a good choice but requires some time to get working nicely.