Rented from SLC for about 30 five day rentals last year... easy to get to, the gold lane isn't very large so depending on how busy it is you may have to get your key from an attendant who mans a key board outside of the gold booth. This happened to me more in the winter and less in the summer (less ski traffic).
If you rent a midsize (picture of the old Mazda 6 on website) be prepared to get a Subaru Impreza. I am PC and I could rarely argue my way out of that one. Also found myself with minivans a few times that I had to argue my way out of. If the gold booth isn't open and you need to swap your car be prepared for some attitude from those at the main desk gold line.
Don't speed coming back into the airport... it drops from 40 to 25 very quickly and I have seen SLC airport police pull into the rental car return while following someone they're pulling over.