Strategies for Classifying 800k HubSpot Contacts into Targeted Segments

We have an 800k Hubspot list and add about 20k contacts per month. We'd like to put these contacts into one of a few buckets like small business owner, big co exec, etc. We get both personal and work emails and I'm trying to come up with a solution for enrichment at the contact level. We don't care about company enrichment except to bring that data into contacts if necessary. I'm thinking we get work emails for those who provide personal and then get their job title, company name, and size of company (employees or revenue) and then use some type of calculated field to group into our buckets. Is this the right track? Any suggestions on how to start? Thanks