We often have Christmas which is just me and DH, plus the three dogs. Christmas Eve we cook the turkey and sometimes do a bit of veg peeling. We eat a special seafood feast and have a bottle of either champagne or Meursault (one of my favourite wines), while watching Muppet Christmas Carol, and singing along badly. 
On Christmas Day we wake up to stockings each - can't lie in too long as dogs usually wake us. One of us makes a cuppa, lets dogs out, then we all (woofs as well) open our stockings on the bed in a big heap, with dogs sniffing things and usually playing with wrapping paper.
We get dressed - dog walking clothes and take woofs for a nice walk - distance depends on weather. Then home, feed woofs and enjoy a late brunch for us of something like scrambled eggs, smoked salmon or similar. Then have a shower and put on some nice clothes/makeup and come back down for a gin. Settle down around the tree with lovely Christmas music playing and will often ring a couple of relatives/friends for a quick Merry Christmas phone call. Then we open our presents - usually assisted/supervised by woofs. This takes a bit of time, as it's very relaxed and we both enjoy watching the other open their gifts. Also make a note of who gave what so we can do thank yous. Then DH disappears into the kitchen and cooks Christmas dinner. I help by laying the table (best china), putting out crackers, keeping music topped up and so on. We usually eat around 5 - it's very special, and we always have a romantic toast to us. After eating, feed the woofs (they often get turkey), do some very desultory tidying, and have a lovely relaxing evening. Depending on what's on, we might watch some TV, but often we'll be reading (often get new books for Christmas).
It's very quiet, and probably wouldn't be to everyone's taste, but for us, it's just perfect, and we love it - my favourite day of the year. Boxing Day is always very relaxed too - lots of turkey sandwiches, usually a few mindless films on TV and a nice walk with the woofs.
We really enjoy the run up to Christmas, and both do things like decorating the tree, DH puts up masses of lights (house is visible from space!), I make a wreath for front door and so on.