How much full sun would these get?

That Spruce /Fir area looks like it is under a Maple? A Hemlock might work well where you want the Spruce, and be much more flexible as far as light and space. A Spruce/Fir will just keep getting bigger and eventually you will have to cut branches and mess up the tree, unless it just grew ratty under the Maple anyway.

Noki, this spot gets full sun from about 12:30 on. The silver maple branches reach over the spot a bit, but afternoon sun still hits the spot where I propose the tree. I'll be pruning back the maple every year.

I've never seen a fir in my area. Does ahyone know of a reason they might do particularily bad here?

Black Hills Spruce is a white spruce that should be easy to find at nurseries in the metro area.

I'd pass on the CO Spruce. Disease prone.

Abies concolor is a nice fir and more adaptable, I think, than the Balsam fir. They are a little hard to find.

Juniper 'Blue Star' is a very nice plant. Great silvery, blue color that gets a purplish cast in the winter.