flightaware.com/live/flight/AAY551 Look at the track log.
Any ideas on the routing/altitude changes during this flight? It took a odd turn near Reno (usually flies straight over), dropped to 16K, then back up to FL320 for a minute. From there it descended into Vegas.
Looked a little weird. Pressurization issues forced a drop in alt? Maybe it’s just a “type-o”?
The changes in altitude issue is discussed in some other topic. (I don’t dare use the S word 
)
As for the odd turn over Reno, it’s not uncommon. Could be some NOTAM or ATC request.
I was on a flight last year that did the same thing and I inquired about it here (CLICK HERE). ATC probably vectored the plane for better separation on arrival at the destination airport. Interestingly, like your example, my flight also went around a major city - Tulsa, Oklahoma in my case.
It happened to me once, in the good old days when pilots could have an open door policy at their discretion.
From CYOW to KLAX, we made a detour around Cincinnati; Later on I asked the pilot why, he simply told me “ATC request”.
Any other reason, I asked? He answered with a sarcastic smile “With the salaries we make, we’re not paid to ask questions” 
If this flight dropped 16,000 feet in 1 minute and climbed back to 32,000 feet 3 minutes later (16,000 fpm again) I think it would have made national news!! Someone would have been injured and/or puked… That’s some incredible performance!! Or a glitch on the altitude reporting…
He didn’t say major traffic but major city.
Don’t forget that Tulsa has a large American Airlines maintenance base. I would imagine that they have a lot of maintenance flights that could interfere with traffic flying over the city.
Don’t guess, you have FA at your service. Look at the arrivals page for TUL. I didn’t see much AA traffic.
Edit: My original post quoted by damiross is deleted! If you look you won’t see it. I didn’t do it. Did FA staff take it out? Oh well!
Ah, but if the aircraft don’t make the national system then they won’t show up.