To expand on onlydarksets' great suggestions:
Here is a link to the PIR FAQ:
FAQs - Phoenix Raceway
Definitely take advantage of the cooler/bag rule. Bring in food/water/etc with you, so you can spend money or other things, or don't spend it at all. And while you can't bring beer in with you (You can thank the State of Arizona for that), it's still an advantage over spending 4 or 5 bucks for a 20oz bottle of coke.
The higher you are, the easier it is to see the entire track. So 20 rows up should be a good vantage point, especially being in turn 1, you'll be able to see the cars come around turn 4 towards Start/Finish pretty easily.
Earplugs are definitely a must. My only experience was at Richmond, and it was quite loud. Louder than I thought. However, since there weren't too many restarts, I ended up taking them out 1/2 way through the race and was fine. Even if you think you'd never ever use earplugs, have some anyways.
If the same is true from my experience at Richmond, they will have the NASCAR Experience set up right outside the track. Food, merch and sponsor trailers and setups. Tons of fun. You can race John Deere tractors, get free tins of dip, and watch a variety of different things. Even if you don't buy anything, it's a blast watching the people walk around. Watch the merch trailers because a lot of times, drivers will come during different times of the day and autograph stuff. My buddy and I busted Robby Gordon's balls when he was signing stuff...he took it in good stride though.
Scanners, radios, etc. definitely help enhance the experience. I didn't use them when I went to Richmond, but my buddy did, and it helped with the stuff we couldn't see (cars disappeared into turn 3 and came out after turn 4, we missed a few wrecks from our seats). If you have Sirius (or have thought about it), they have the race, along with several drivers scanner frequencies during the race.
As far as traffic goes, think of it like a tailgate. Take into account that it's going to take at least an hour to get completely out of the complex, and go from there. Richmond sucked because it's a haul and a half from the track to their parking lots. But as long as you account for it, it shoudn't be too bad.
jsarno - going to a NASCAR race is a helluva experience. Enjoy it to the fullest.