Where are you located (nearest big city, state)?

Here in NC the oaks are the last to go.

@cecily 7A Zone 5b, Colorado Springs

@Christopher CNC Do you know which species of oak they are?

In northern Virginia, the oaks are last to turn and then hold tattered brown leaves all winter LOL. In Colorado Springs, I'm sure you have other choices.

Some oaks will hold the leaves, most don't. Here we have red, white, chestnut and their hybrids at a minimum. Lot's of oak species. Their colors are in the red, orange, brown, russet range, Not the most colorful of the trees, really kind of brown.

You should look at oaks native to the front range and rocky mountain region.

see if you can locate any tree farms within a few hours.. and then drive to them ... at the time period you wish to see color.. and then buy one for delivery in spring .. or the appropriate time for planting whatever you choose ... the bonus is.. you can write it off a a fall color tour daytrip ....

the alternative would be to keep your eyes peeled [boy that is a lost phrase]... and take pix in parks or the neighborhood.. and let us ID what strikes you ... we would need a pic of the tree ... and a leave.. with a scale ...

this is my go to... whenever peeps want specific maples for fall color ... go to the nursery.. and pick one when it is in color ... otherwise you are left to the3 vagaries of nature as to what you will end up with decades down the road ... but just because you find one.. might not mean it is the proper time to plant it.. e.g. with oaks... late fall is not prime planting time ... note section 1 at the link below.. and the rest for general knowledge ...

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

For me, NJ/Zone 7b, Japanese Maple Bloodgood and Dawn Redwood (a tree that needs SPACE), both peak in November. The Japanese Maple goes from plum purple leaves to scarlet red leaves that are held on the tree for a few weeks and the Redwood changes to bronze leaves. My Crape Myrtles also seem to take on color rather late into Fall.

It's the Pin Oak that looses its leaves last; in the spring. But does it change color last? I can't remember. I do remember all winter trees full of brown leaves.

Currently Im considering going with a European Beech and a Sweetgum tree, as Ive heard they hang on to Fall color later

@Christopher CNC The oaks native to the Rocky Mountains and front range are scrub brush. But in neighborhoods developers put down a foot or so of good soil with ph around 6.5-7. So we can plant just about any tree that will tolerate 5b.

I trust your sweetgum is a sterile cultivar.

@cecily 7A Why is that?

Sweetgums can produce an abundance of extremely annoying spiky seedballs. There is at least one cultivar that is fruitless/produces no seedballs however many people deal with these trees without issue. Depends on their tolerance level :-)

A sterile round lobed Sweetgum like this one in one of the gardens I tend

Round-Lobed Sweetgum (monrovia.com)

is 60+ feet tall at 25 years, has never once had fall color in 14 years and holds on to the frozen brown leaves all winter thinking it's a Pin oak. Plus the roots sucker like a cherry and the suckers have normal pointy lobed leaves which might have fall color like a normal sweetgum is capable of if I wasn't always cutting them off.

@Christopher CNC Do normal sweetgum trees sucker too?

I would not recommend a southern water loving tree like Sweetgum for Colorado Springs. Wrong zone, wrong climate. Ken's advice was good. Go leaf peeping this fall and take names. Plans for a spring planting might be better for establishing a tree in your arid zone 5b.