FYI. A few weeks ago rented a comact in DIA for $376, 22 days.
Have used them at SLC many times, always OK.
Advantage is Hertz's discount brand. Only downside I've experienced, the cars are usually a long way from the terminal.
In Denver it probably won't matter, because you have to shuttle to all of the cars. In SLC, it's a bit of a hike.
I also use Alamo Insiders. You get your pick of cars and 2nd driver is free, which is usually $15/day.