SSAS - what could I monitor in SSAS to fine tune its memory settings?
When trying to fine-tune your memory settings there are two things you'd want to watch:


MSOLAP Memory counters for your server in Performance monitor





Specific DMV queries over discover_object_memory_usage rowset and discover_object_activity rowset. 


You can always use a third-party tool to monitor your resources. Also, you might want to check out this article – it gives a detailed description on how to achieve exactly what you are looking for.