Good question, Scott. The only thing of real value I didn't sell in my first collection sale was the Horner Composite hanging on my wall. But I am not even necessarily married to it. It is awesome and I love it...but it could be replaced by a new piece, though I am in no hurry.
Maybe the baseball card hobby periodicals/ephemera collection is something I will keep as it is so intriguing and so unique. And I don't guess all that valuable, relatively speaking.