Vineyard Garden Center (435 S Geneva Rd, Orem, UT 84058 (801) 225-4357)
Noles Nursery (1915 E 6400 S, Salt Lake City, UT 84121 (801) 278-1237)
J&J Nursery (1815 W Gentile St, Layton, UT 84041 (801) 544-1211)
My favorite place to buy yard stuff is J&J. They have tons and tons of plants and 40-ish acres of land out back that you can roam through to find the perfect tree. I have bought many things from them and will continue to do so.
I have also bought from Noles and Vineyard. Noles is a family place with the back yard full of trees. They seem to have less of a selection but are often larger trees to start with.
My parents and siblings have bought a lot from Vineyard but its been a while for me so I couldn't really say what they seem to have in stock.
I'd recommend staying away from Glover and Wasatch Shadows as I have found their prices do tend to be pretty high for what they offer.
It is still fairly early for trees and the places will just start to get their shipments for the season in. For Utah, most of the trees come from Oregon/Washington.
What I like about J&J is that they buy trees then have them on their back property for a while (multiple years often) to acclimate to Utah climate. From your post it sounds like you want something big from the get go.
I'm not sure exactly what your reasons for this are but its a lot easier to keep a smaller tree alive than a big one. I'd suggest going smaller for price and ease of care.