[El Cid]

Re 58, 66, etc...
...What activities, that are licit on other days, would detract from the holiness of the Sabbath? Do parishioners have to just sit around all day in contemplative meditation, or is it permissible to go do something like take in a movie, rock climb, skeet shoot, kickbox, have sex, or even (gag me) breakdance?

Its entirely your call. I'd just keep Isaiah 58 in the forefront of your mind:

Isaiah 58
13 If thou turn away thy foot from the sabbath, from doing thy pleasure on my holy day; and call the sabbath a delight, the holy of the LORD, honourable; and shalt honour him, not doing thine own ways, nor finding thine own pleasure, nor speaking thine own words:
14 Then shalt thou delight thyself in the LORD; and I will cause thee to ride upon the high places of the earth, and feed thee with the heritage of Jacob thy father: for the mouth of the LORD hath spoken it.

[cyclotic]

I was talking strictly New Testament. Christians are no longer under Old Testament law