Collectd + Graphite / InfluxDB + Grafana. You shoudn't need to ssh on a host to see those metrics.

Stackdriver, boundary, signalFX

glances? https://pypi.python.org/pypi/Glances

pip install glances.

Agreed, considering they've built Vector (mentioned by bgregg in the second sentence - https://github.com/Netflix/vector) on top of Performance Co-Pilot. While PCP doesn't yet have all the wrappers to mimic each sysstat output in a fully compat manner. The underlying mechanisms to remotely fetch that data (using the tools Vector is already built on), is already there.

glances. Mentioned elsewhere in the thread.

Very nice. https://github.com/nicolargo/glances/

I like how there are configurable alerts for each datapoint, that's a start for analyzing what's wrong.

There is - software like Splunk, SysTrack, etc. get towards that in various ways.

There is, look up Conky

Conky doesn't tell you what's wrong with your system (À la powertop 2.0). It just present the information differently.

Conky is for your desktop. We are talking about a server, which you connect to via ssh.

nmon

maybe monit or something similar (inspeqtor etc)