I often find I have groups of layers I would like to turn on or off together. I tend to use a name prefix to make it easier to do so, but it would be nice to be able to Ctrl-Click and group layers together in named groups, so that you can turn on Visible and/or Editable attributes for all the layers in the group together (obviously you could also select them individually).

Initially, I was thinking that a tree structure (like an outline) for layers would do it (and that wouldn't be a bad idea, perhaps as well as grouped layers), but sometimes layers that should be turned on together are interspersed with other types of layers.