Good suggestion with respect to DSC or Reno. Most of the current makers will be there with rifles to pick up and get the feel of. More importantly, so will two or three of the major dealers in quality used SxS rifles (well, maybe not a Sabatti)
In particular, JJ Perodeau helps man the Champlin Arms booth. They will have some great guns, but more importantly, JJ knows more about doubles than anyone else that I know in this country - and he is the only person on this side of the Atlantic that I allow to repair or adjust one. Pick his brain.
Finally, buying a used double can be a great deal, a catastrophe, or somewhere in between. My own education took several decades and more of an investment than I care to think about. Pay to have someone like JJ go over it before concluding the sale. And as I say, he is the only person I would use on this continent.