Every day has its own feeling. Saturdays feel different from Fridays feel different from Tuesdays, and this is true even when you're not working regularly.
I generally resent Sundays. The feeling on Sundays is that there is nothing new happening, that the world is holding its breath until Monday. After 2pm or so (when we've barely returned from church) it feels like nothing can possibly happen with the rest of the day, because there is no news, no social media, no chat, no email.
Today, I spent a good deal of time reading a large chunk of two different books, and a couple long-form articles I had on the burner. I also spent, and will continue to spend quite a bit of time writing. I think it's best, perhaps, to spend most of one's time on Sundays accepting the fact that there will be no external novelty, and, accepting that, spend your time in meditation—whatever form that may take. Religion, reading, writing in depth and so forth are all good places to be; the other days of the week can be for sharing and collecting and living and moving, but Sundays lend themselves to living inside your own head.