My late wife and I always kept Sunday's as we had been brought up to. We had a nice lunch (or dinner once the kids were no longer at home) the children were discouraged from noise and frenetic activities, it was a quiet day. As for shopping, unless there is a desperate food shortage (i.e. no milk) in the house, shops were, and still are avoided on Sunday. I had occasion to go to the 'blue and white shop' one Sunday last year and it was like a zoo where someone had left the doors open to the monkey enclosure!
For me, it is now a day for odd jobs on the allotment or in the garden and sometimes when my conscience allows, I will spend time in the workshop. The cat lets me know when it's time for a cuppa or some lunch but yes, I agree with Mark, I like the tradition.
Dave