Entity Inheritance

One request we seem to see a lot from our customers is the need to have different flavors of accounts and contacts.  For instance, an account may be a financial institution, a tenant, or a vendor.  We could create three different custom entities to represent the uniqueness of each of these account types, but we would then lose the built in functionality regarding an account in Microsoft CRM.

Alternatively, we could add attributes to the account entity to fulfill the needs of each account type..  However, that would result in having attributes that apply to one type (say tenants) visible for another type (say vendors).  That might reduce the usability of the system.  Granted, we could create a tab for each account type and hide / display the tab based on the type selected.  This is a valid approach, but still requires quite a bit of custom client side code and does not prevent the unrelated attributes from showing in other areas such as the advanced find or system views.

I would like to hear how others have addressed this question.  Ideally, I would like to be able to inherit from the account entity and create custom entities that are based on account.  Unfortunately, this is not a supported customization and may not be possible in the current version of Microsoft CRM.  Please share your solutions, as this is probably a question many of us have had to answer at one time or another.