I've sat in most of the end zone sections in the North end zone for past Cardinals games. As long as you don't sit directly behind the uprights, you will in all likelihood enjoy your seats. There are a total of 41 rows in almost all of the lower level areas and rows 15-22 are the best in my opinion because they're close but also not too close. I also love the open area of the concourse in the North endzone. Plus, there are plenty of concessions and restrooms just a short walk away. Just skip visiting them at halftime.
There are a few nice features I particularly like about UP Stadium that you won't find at other NFL stadiums you visit. One is the various murals on each level that display aspects of Arizona. You will notice these when traveling up the escalators. The other feature I really liked was the statue of former Cardinal Pat Tillman outside of the stadium. He was a true American hero and there is also a statue of him on the property of Arizona State University where he also played.

This place gets a lot of attention for having real grass instead of astroturf/fake grass like so many other NFL stadiums. Instead of opening the roof to allow for sunlight to get in, they cart off all of the grass to outside which saves millions of dollars in operating costs of the roof. Sounds like a lot of work but the playing surface always look perfectly trimmed and healthy.