I have a Stout fermenting away that I plan on adding cherries to. Of course, if I come to my senses, maybe I won't.

Now I can easily add packaged, grocery store, frozen cherries to a secondary fermenter, rack the beer on top and let whatever happens happen. Seems easy enough, but maybe...not so fast?
My biggest concerns are:
1. I really, really, really want to avoid any medicinal, "cough syrup" flavor in the finished beer.
2. IF packaged, frozen cherries are not "clean" enough, I'm concerned that a "sous-vide" type sanitizing step will strip some flavor away.
Yes, there are other options for adding cherries.... Fresh, cherry juice, extract. I'm not opposed to any of them, though the medicinal concern remains, even more so with extract. And I suppose I missed the boat for the best fresh cherries.
I don't
need to add Cherries. I can go with Raspberries or Cranberries instead.
Or nothing.
Thoughts?