What should I cook for Christmas dinner?

I was thinking about a traditional roast. I'll start the marinate tonight so it will sure to be done by Christmas. I don't know if I should add the potatoes to the crock pot too or just have them mashed instead. And maybe some french bread instead of dinner rolls, g salad, magic cookie bars and chocolate chip cookies for dessert for sure. With the roast will be carrots, celery, and onion. I'm just stuck on the potatoes. I want to make a nice dinner but just not sure on what to make cause it's just the 4 of us...