It's a very pleasing image irrespective of vignetting. Individual taste I suppose will dictate whether you remove it or leave it: my taste is leave it.
You probably couldn't get a more atmospheric and "big sky" place to unleash a camera — any camera — than your location in the desert of Arizona. Most of us down here, Dowunder, would kill to photograph those places, among others, Monument Valley, Grand Canyon, Yosemite (and do it darned well better than Uncle Adams!!), Slot and Antelope Canyons... would be criss-crossing the USof A very frequently!!
Poisson Du Jour, Thanks, I'm glad you like the image of Superstition Mountain. It's located about 15-miles from my house and has an elevation of about 5200'; I hiked to the top one winter, the last two-thirds of the hike is more of a climb, hand-over-hand in some places. I've also hiked the Grand Canyon and Yosemite and been to Monument Valley; all wonderful places. If you get a chance to visit, come in November, our best month when the temps. are pleasant. And if you do visit, drop me an e-mail and I try and steer you in the right direction. - - Jonpaul
The main thing is to keep the main thing the main thing.