Both would prefer partial shade as opposed to heavy shade - the crossvine won't flower heavily and the V. creeper won't develop much fall color in excessive shade. The creeper (Parthenocissus) is deciduous and can be invasive in some areas. Check your local noxious weed listing before planting.

I would think twice about virginia creeper. I can't imagine you would ever see your trellis again.

A friend of mine has virgina creeper growing up over and around her garage doors (in half-day sun), and it is gorgeous! She planted it in a small contained bed by the front door, which has the house on one side, the cement porch on another, and a brick wall and brick sidewalk on the third and fourth sides. She ran the VC along the back of one of the two front steps, and then trained it up around the garage. It really isn't all that much work to keep it in check *in this situation* and truly looks lovely. I'm thinking of doing the same to my garage.

That being said, while the VC would most likely do well in the shady area, my fear is that it would do TOO well! I have VC all over my woods, and I often have to hack it back from spreading out into the lawn. It doesn't bother me that much, but I don't know that I would voluntarily plant it in an area that I might not attend to that often, i.e. a naturalized area. As sugarhill says, you may never see your trellis again - at least not without regular and consistent attention.

Sure is pretty in the fall though - mine gets pretty good color even in the woods. Sorry, can't help with the crossvine. Good luck.

Dee