You can check regional adaptations using this.

Here is a link that might be useful: Find the perfect plants and flowers for your garden

Red Tip Photinia is not really fully cold hardy anywhere in Zone 6 if you want it to be a screen that doesn't freeze back in cold winters. All the photinias in the Boise area froze back at -7 degrees about three years ago. They survived and sprouted back up but that is usually not what people want from a screen. I predict with the -7 to -10 degrees this past December in the Boise area that the Photinias will again be severely damaged and need to resprout from the stump. Not exactly what you want from a screen. Manhattan Euonymus is a broadleaf evergreen that is much more cold hardy and works as a screen even in places colder than boise.