Thanks Bridie and Melissa. I considered both of those categories too.
I decided to submit two industry suggestions to LinkedIn. One is "Virtual Assistant" and the other is "B2B Services" (this has a broader audience so may have a better shot at getting accepted).
If more people submit the suggestion for "Virtual Assistant", LinkedIn may just listen.
Here's how to do it:
From your LinkedIn home page look at the bottom of the page and hit "Help Center". Then type in the search box "Industry". You'll see a link for "Suggesting a Missing Industry". Click on that and once you've read the blurb hit the "here" link and type in "Virtual Assistant".
They give no promises and no feedback. It may show up as a category on the list one day, or it may not. But hey, nothing venture nothing gained.