I'm surprised to read all of this bad about SLC, this is the usual way it went when I went it,
I would descend from over parley's summit from around 10K they would have me get down to 5.5 east of I-15, as I would reach I-15 still headed west, the would clear me to enter right base for 35, I would basically go strait in from parley's canyon.
Leaving they would clear me right turn out climb to 5.5 and contact departure, after contact they would clear me east with unlimited climb.
Strait in and out.
When going to U42 from parley's canyon, they would basically the same thing but have me go strait to the south interchange, were the would clear me at I think 6K strait to U42 for a left base 16.
My instructor told me it was cause the way I would talk on the radio, cause I was trained by high time 121 and corporate guys and they would ride me on everything they could that had to do with comms, fast, precise, exact order, and clearly. It worked great for me. During the whole flight even when performing maneuvers they would quiz me with silly ATC instructions, and if I didn't do them all right then we would have a bit of ground talking about the order and clarity that I needed to work on.
They were always great to give me what I asked for, one time my wife wanted to do some photos of downtown, they gave me everything I asked for. Capitol, Rice Eccles, we spent about 30-45mins in their airspace going all over and changing alt, just told them nicely that we need to do some photos and the were great.
And while doing my IFR they were great to work with, my transponder kept messing up on me, and after the third day in a row, they asked me to please get it fixed, after droping of my instructor, they cleared me to land there since thats where I needed to go for a good shop to fix it.
I am not sure why others have had problems, but I would bet most are flying in the centers club, and I have heard rumors that SLC don't like the air centers instructors. Granted it was just rumors never went up to the tower and asked.
If you ask me this is one thing that is lacking with most instructors at u42.