Hootsuite Pro is used as a tool to schedule and monitor Twitter and Instagram mainly. We also use it during Twitter parties and to track hashtags. The newly added feature to schedule Instagram posts for biz accounts was a very welcome update.
The most used feature for us is scheduled tweets and Instagram posts by far. It's also very practical for twitter parties and tracking hashtags and conversations. Since each platform offers their own analytics we don't use Hootsuite's analytics as much. In the past, we've used it for Facebook pages but I find it easier to work directly on Facebook for that.