I would use dom!Dean to mean that Dean was the MORE aggressive or dominant partner in that pairing - just for clarification. ;) And I don't know, maybe I'm weird and most people don't do it that way, but actually these days very few of my fics contain actual sex at all - and I still use those terms to define the dynamics.

I was looking through the comments and like a couple others said "Toppy Sam" or "Toppy Dean" is also a good option especially for when there's little to no actual sex. :P