How to Control my Tags with Custom Taxonomy?

I have more than 200 tags on my site. I’m looking for a way to give editors an alternative to picking through the mountain of tags available. My thought is to use custom taxonomy to narrow down the choices somewhat.

I’d like to begin by creating a “People” taxonomy that could hold all of the people mentioned in articles. My only concern is whether those “people” can be dumped back into the main mountain of tags. I use tags for SEO. (or is there a SEO plugin that can recognize multiple custom taxonomies?)

Thanks.