I have a database where I want to be able to search several different types of documents-- faxes, memo, letters-- but want to display each in their own specific format. At the same time, I need an overview directory to display information by project, etc. regardless of format.

Can I set the view to a given record by a variable (document type) or would I do better to have separate related files for each layout type? And if so, is there an easy way to implement a find across all of them using portals or the like?

Your wish list is absolutely feasible. With a variable for let's say DocType, you could return the results of a Find in a list layout, sorted by DocType if you like, and/or any other criteria. Make a button that goes to the detail layout with a script like:

If (DocType = "Fax")

Go to Layout (Fax)

Else

If (DocType = "Memo")

Go to Layout (Memo)

Else

Go to Layout (Letter)

End If

End If

That's one way to do it. You could do something similar with a portal.

I'd imagine that faxes, memos, and letters are similar enough that separating them into their own files would not be the optimal solution.