How about this:Create a simple classification of "Company Name" called, say, "Company Group" (or whatever makes sense to you).Create a spreadsheet where each company that needs to be in your segment has a "Company Group" value of "yes".Upload the spreadsheet using the Classification Importer.Create ...

I feel your pain. Workspace downloads with multiple dimensions are ugly to clean up. I second Pablo's suggestion to use Report Builder. That's pretty flexible, even if configuring a report is a bit ungainly. Data Warehouse would work too, but it has some annoying limitations.

Sounds like a good use of a classification. You can copy the "Regions" value into an eVar and then use a classification to roll those values up any way you'd like.