Wow 64GB of RAM is like a dream.  Right now, we use VMs, which we could get more RAM for, but there's pretty much no business case for more RAM unless the server is getting overloaded on a regular basis.  Our biggest database is currently running on 24GB, while the database size is ~300GB.  So yes, we could put the whole thing in 1TB RAM, but that's not even a remote possibility.