Dave Woodard would never have been killed!
Granted, a different actor was playing him by that time, but I still have a picture of the original Woodard in my mind, and his death is just so terrible. I'm not sure how his fate might have been altered, perhaps he might have somehow been brought in to the secret and helped Julia find a cure for Barnabas. I really like him and he was intelligent and kind, providing a somewhat calming influence on the show.
I was also very sad to see Sandor die. He and Magda had a great relationship that was so much fun to watch. I loved that character, couldn't they have found some way to keep him around?
I would have kept Chris and Amy at Collinwood. They just disappeared one day, with only a comment from one of the characters to tell us of their departure. Not to mention they never solved Chris's problem, and after focusing on it for so long, they should have. Rather annoying really!
They were such excellent characters,, I missed them when they left.