I love to follow a tradition with set pieces even though they are a bit stressful. Agenda for Christmas is meet, snacks, eat, open gifts, tea or coffee, leave. I try to stay home for the rest of the time and lay a couple of 1000 piece puzzles, watch some shows and relax at home.
New year's I go for moderate drinking and watch Áramótaskaupið (Icelandic New year's sketch show) then watch the immense amount of fireworks people blow up at midnight. After that head to a small party for a couple of hours as a reunion and at 3am go home and have a short video game session.
It sounds like a lot but since it's always the same and there's no loud music at any point it's manageable. :)