Quick question for anyone who may have done this already.
Does anyone know of a way to automatically have vCenter export weekly performance charts for certain VMs or even the individual hosts?
no, not using vCenter itself. You would have to get some sort of monitoring/reporting tool.
...you may be able to get useful information using PowerCLI, such as below
http://communities.vmware.com/blogs/Paule83/2010/02/15/monthly-statistics-on-cpu-and-memory-load-of-esx-hosts