not too many expectations.. eh??? ... lol ...

anything that is known to grow fast.. will just about.. rule out all your other wishes...

do not buy a 'fast growing tree' ... many trees.. grow just fast enough ...

and as to climbable... the kids outgrew everything i planted 14 years ago ... now they wont turn off their computers .. and go outside ...

ken

Agree with Ken. Fast-growing also usually means weak-wooded, and prone to breaking apart in storms. Silver maple comes to mind as an example, but even that would take years before you can sit under it. It's native, but many people consider it one of the worst shade tress to choose. Doesn't have fall color to speak of either. I don't think you'll find a tree that you can plant now and sit under in the foreseeable future, or have your kids climb on before they outgrow that interest.

Gingko is beautiful (although not native), but if you get one, make sure it's male, or it will violate your wish no. 1 big time...

If I had room and need for more shade trees, I would plant a Yellowwood (Cladrastis kentuckea).

I've read that Ginkgo may take 2 or 3 years to sit there, adjusting to transplant, and then start growing at a moderate rate. I think somebody on here once posted of one growing about 18 inches/year, for whatever that anecdote is worth. So not fast growing.

As for spiky, be mindful of cultivars that may avoid the product - Rotundiloba in Sweetgum, some Honey Locust, etc... So even if a species does something, maybe there's a cultivar that does not.

I'd forget underused; you're trying for enough criteria that you can't be too picky.

What do you consider messy? If acorns are a big deal to you, that would write off the oaks, which is sad, since that might be a good option otherwise.

Forget anybody climbing it but the grandkids, if your kids are little now.

I don't know what prospers in your area. Some trees with a rep. for fast growth that I don't hear much about being weak wooded include red oak group, maybe red maple, tulip poplar, sycamore, dawn redwood, lacebark elm.

How dry is your soil? Any idea how alkaline? Are highs around 100 typical for you in summer?

Richard.

Unfortunately, #1 contradicts #2 and 4. The best thing for wildlife would be a native that produces berries and is evergreen to provide shelter...berries can get messy. A seed grown/species native is more "earth friendly" because it might interbreed with neighborhood trees and broaden their gene pool.

A bit small, but what about
Washington hawthorn (Crataegus phaenopyrum)?

Common Hackberry (Celtis occidentalis)

Not native, but crab apple are good for climbing and wildlife like them.

Thanks everyone for your advice. I'm dropping all the requirements except for shade. And I would like either fall color or attractive to wildlife.

Richard, temps are 100ish all of July and some of June too. I'm not sure how alkaline, I just figured it was alkaline because it's clay.

A red maple sounds nice. From what I'm reading it seems that I can grow Autumn Blaze here. Grows moderately fast, tolerates clay, nice color, low maintenance and the size is right. For some reason they seem not to be liked on this forum. Maybe they are over used?

Also considering the tulip tree although I'm worried the size is too big for my space. The corner I have picked out is a triangle at the junction of the fences, measuring 12x12x12'. Bummer that the flowers don't come for 5-10 years. Also the weak wooded thing is a concern because we have high wind here sometimes. Any thoughts about this?

What suitable trees are naturally native to your area? That would be a good start. Unfortunately, I am not familiar with what trees are native to Utah.

Bur oak would be among my top contenders - and it's on the Utah list.
Very tolerant of soil type/pH and drought-resistant once established. Among the fastest-growing (2+ft/yr) - and longest-lived - oaks in my part of the world. Not much for fall color, but looks great the other 50 wks of the year; multi-season interest.
Produces 'sweet' low-tannin acorns that are relished by deer/squirrels/turkeys, etc.

Bur oak I think is too big for my space. I think esh_ga's suggestion to start with the natives is what I will do. I'll go back over that list I have, this time only looking for the *real* requirements: shade, spread, and not slow growing.

thanks everyone for the great suggestions, learning a lot here.

I've decided to go with Chitalpa. It's the perfect size for my yard, grows fast, clay tolerant, under utilized in Utah, and attracts birds and bees.

Sounds good!

What about Bigtooth Maple?

Acer grandidentatum. A Utah-native alternative to the eastern Sugar Maple - with the same fall color, higher tolerance to heat, drought, and high soil pH.

hairmetal4ever-

Is this maple like the others in that the roots won't allow any other growth? I have a veggie garden that is 20-25 feet away and I wouldn't want the maple to suck all the water away from those plants.

Somewhat, but probably not to the degree of, say a Silver Maple, but I can't say for sure.

They're not huge trees, so 25' away may be OK, especially if in a sunward direction.