Separate VM's under the host for each, I don't nest vm's under vm's. Maybe if I were trying to run esx under the parent to play with vmware or something, but as you said, not common.
I have some spreadsheets that drive libreoffice absolutely batsh!t crazy, mostly doing a complex concatenate to generate switch configs off some columns of data. Doing so still causes libre to wretch and lag and hang and use a globs of cpu/memory for some reason. I write it off as a peculiarity of libreoffice, which I've just not tried elsewhere to see if any better. More often than not, I find office is worse, or different enough to just break my formulas.
Cisco price lists kill it with just sheer volumes of rows...
-mb