We don't do a Sunday roast anymore - for various reasons.
But even when we did, Christmas dinner was more special.
We never had starters weekly - maybe on a special occasion. But always have smoked salmon on brown bread or else prawn cocktail on Christmas Day.
Rather than 1 meat weekly, Christmas has turkey, usually ham, and probably spiced beef. If reduced, ham is first dropped. If we go "home" to our DPs, all 3 are on the table.
Proper gravy. DM makes giblet stock for the purpose. I make giblet stock for the purpose. Meat juices are added, and a slug of wine in my case. (I would generally have decent gravy with a roast, but it is different somehow).
Sundays are 1 or maybe 2 veg dishes. Often 1 is a mixed veg, so not totally boring. But Christmas has sprouts (not the only time they get eaten but not everyone does here), a mixed roasted root veg, and cauliflower cheese - at least. I may do another veg dish. Something like French beans with bacon and cream, or plain peas, or glazed carrots, or steamed brocolli.
LOADS of roasties - but proper full sized potatoes. Regular roasts are smaller so I tend to cut the potatoes for faster cooking.
I rarely do stuffing, unless its a chicken AND I feel like it. But have to have stuffing with turkey.
Yes, to nicer wine - I buy 2 bottles (in case we feel like opening the 2nd) in September and put them away. I also buy a half bottle of dessert wine, for with the pudding - and that's the only bottle of that which I buy in the year.
Cheese board, then pudding.
Nicely made table. The good crockery, a particular set of wine glasses (we do use those occasionally during the year but it is not often), candles.
And also a sense of not having to rush anything. We start cooking when we get in from visiting, have nibbles to keep us going until its ready, so it can take as long as it needs, and then we are relaxed and enjoy savouring the meal whereas Sundays do tend to be more rushed.
(We are also usually looking forward to a specific other dinner, later that week, using turkey stock and leftover ham and leftover (?! - specially bought!) stilton to make a festive potato gratin dish.)
It is probably the only meal in the year where there are no expectations and where we have no other things that need doing which are distracting us - so that is probably the thing that makes it most special for us.