Question
I have a fence about 6 feet tall and a trellis about eight feet. I want a rose to climb up the trellis and along the fence. Since I live in South Dakota (Zone 4), I know I can't be too picky because winter hardiness narrows my choices.
I absolutely love New Dawn, but am I correct to believe it won't weather the winter well? John Davis or John Cabot are options, but will either be able to make it up the trellis?  
What are your ideas?

Also, I would like to grow a rose across a one-story wall of the house by the back door entrace to be the backdrop for a garden bench sitting area. I was thinking that if Cabot worked with the wall, I would use Davis with the trellis, but is height an issue here as well?

Thank you so much. The more I read, the more confused I seem to get.  

Answer
You are correct that in a climate that gets a very cold winter you don't get a big choice of climbers. Mainly because they grow so far out of the ground and so get killed by the cold winter winds. You can of course dig one side up and lay them down but that is a heck of a lot of trouble to go through both in the fall and the spring. New Dawn doesn't do well past zone 5 and sometimes even complains in that zone, depending on growing conditions.
The best ones for your area, and the ones I get the best reports from are, William Baffin (he can grow large) and John Davis, he grows like a pillar. People say they like the looks of his flowers and that he also blooms a lot. John Cabot is also a good one and grows taller and spreads far more than John Davis.
Never pay attention to what the rose books or cataloques say about the height of a climber.  These roses can be kept down to where you want them by pruning hard in the spring.
Hope this helps. Lynnette