Any recommendations for tall columnar non-invasive trees?

What do you mean by "tall" and do you want coniferous? Also, presume you are considering the grassed area - what is the maximum tree width you can tolerate in that spot?

Some cultivars of Hoopsii Blue Spruce or Fat Albert blue spruce will reach 20' in height and, at maturity will reach up to 8-10' in width. Picea Pungens Fastigiata (Columnar Blue Colorado Spruce) will be shorter but narrower at maturity. All of these would eventually make great trees decorated for Xmas.

Emerald Oak or Columnar English Oak meets your above ground needs, no idea on the root structure.

Weeping white spruce (Picea Glauca Pendula) would fit perfectly in that space but not entirely sure about their roots. They get about 20'x5'.

So close to the driveways, salt will be a problem if you use it. 8' is really narrow, not sure what will thrive in that space, the weeping white spruce can reach 10' wide, and many of the columnar oaks get 15' wide so check the specific variety if you choose a columnar oak.

Roots extend beyond the tree canopy, so that may be an issue for your driveways, but I wouldn't worry about the house.

Good call about salt although I think they use a lot of sand in Alberta because it gets too cold for salt to do its thing. Snow would be a pain in general with a conifer though for shoveling.

I planted a couple of 'Green Pillar' Oaks in my backyard. They are one of the narrowest Oaks you can get. How well do Oaks grow in Alberta OP? That climate is very hard on trees, dry, cold, massive temperatures fluctuations in short time.

Thanks for everyone's input!

I went on another gardening forum and someone suggested Pillar Birch trees as a good non-invasive option for Calgary.

My neighbor and I don't use salt on our driveways, so it shouldn't be an issue.

Copper1212 wrote: ↑ Good call about salt although I think they use a lot of sand in Alberta because it gets too cold for salt to do its thing. Snow would be a pain in general with a conifer though for shoveling.

I planted a couple of 'Green Pillar' Oaks in my backyard. They are one of the narrowest Oaks you can get. How well do Oaks grow in Alberta OP? That climate is very hard on trees, dry, cold, massive temperatures fluctuations in short time.

Oak trees do quite well in Calgary, but they're too wide for the area we're considering. Although we want the trees within the 8-foot grassy area, we'd like something as narrow as possible so as to not interfere with cars on the driveways. I'm considering an oak for the back yard though, so good call there!

Not all cultivars are wide. The one I mentioned stays very columnar.

Irish Yew. They grow well here in BC where I am, it usually doesn't get colder than -15C (unsure about Calgary). Slower growing and easy to keep pruned to the right size. Looks better than cedar. I have a couple and they can grow 4' wide but are easily kept to 2 - 3' wide with an annual trim. I keep mine 6' high max because they can get damaged by heavy wet snow.

Smaragd and pyramidal cedar is what most people use here but they can slowly get over 6' wide and 20' high if not trimmed. Lots of people are slack and end up with oversize hedges between houses and driveways.