We like the 3 envelope Pot Roast on a regular week day roast, I just do all this in the crock pot. If I have more time:
I like to brown it in bacon grease first (just fry some bacon, remove and then brown the roast in the drippings).
If adding veggies, I put the potatoes in first (if in crockpot, at the beginning; if on the stove, after its been cooking a little while). The carrots, I will caramelize them first.
Heat butter or the drippings from the roast (when you browned it), add the carrots (I use tiny baby carrots) and let cook and caramelize and then add to the roast.
I THINK the browning and caramelizing carrots came from Pioneer Woman but not completely sure. I am always getting recipes or methods of cooking from here or there and can't remember for sure.
And some body (Rachal Ray, maybe?) says to add a TB of tomato paste to it and I do sometimes. I can't remember what its supposed to do though! Something about adding the acidity of tomatoes, maybe? Maybe its that different "depth of flavor" that chefs are always talking about. Anyway, it is good with the 3 envelope method and other methods I have used.
For some things, I like to combine different methods rather than following one definitive recipe.
If I was doing something new for Christmas dinner, I think I would try it on a smaller scale on another day. But, that's just me and my mixing of stuff so YMMV on that one.