So I recently went to the Bannered Mare in Whiterun after learning that not only can you cook with the ingredients given, but there was a cooking pot there. There I met Saadia. No matter what I do, she won't accept my Amulet of Mara, even after I finished her quest and let her live. Is she a marriable character in Skyrim?
She's not marriable. You can view the full list of potential spouses here.
No, unfortunately Saadia is not one of the female NPCs you can marry.