Recommendation for custom fields to segment accounts/contacts by specific criteria.

Recommendation for custom fields to segment accounts/contacts by specific criteria.

I am toying with the type of custom fields to create in the Accounts and Contacts modules to indicate some specific criteria the Account/Contact might meet. For instance, I have several Accounts that may have a specific group affiliation or have won a specific award (or they could meet both criteria). Keeping in mind that they might meet more than one criteria, I'm torn between creating Check boxes for each item, creating a Multiselect Pick List with all the options or a single select pick list for each item.

Overall, I DON'T want to gunk up my data, but need a clear way to segment the accounts or contacts that meet these criteria. Any recommendations?