Salesforce is extremely flexible. We have customized it with several integrations to help us manage our internal sales workflows and processes.The Lightning interface in Salesforce is a great improvement in terms of UI and we're looking forward to the Winter '17 release!
Unbounce helps us create and host landing pages. The analytics and integrations (e.g. Salesforce) provided by Unbounce have been very helpful in helping us monitor campaign metrics.
We evaluated other tools but eventually selected UserVoice. It helps us document and track customer feedback. Our users can submit feedback directly through a widget that is embedded into our Loopio platform.