back to nature, but since you asked:

Red Rock Canyon, Mount Charleston and Lake Mead are all within a very reasonable drive time to LV.

Been there a few times and loved it each time.
The colours are amazing.

Red Rock Canyon is closer. I have been there many times, and always enjoy the lovely scenery.
Done a couple of hikes there, and seen a few wild animals over the years.

Mount Charleston is always a nice place to visit.
Its around 20 degrees cooler than Vegas, so worth going when its to hot elsewhere.
A few nice trails to hike too.
First hike I did up there was the Mary Jane trail.
Only a six mile round trip, and good for beginners.
Also worth driving around to see some of the beautiful houses around the area.

This past December I went hiking over at Spring Valley Ranch State Park, which is around 15 miles west of Vegas.
Some nice scenery to see there.

Lake Mead is always worth a visit if you like water.
Nothing better than splashing around on a jet-ski with the sun blazing down and the water spraying your face as you zoom along at 40mph.
Lots of fish and a few feathered friends to see along the way.
you can also get close to the rear of the Hoover dam.

Closer to home you can visit the Flamingo wildlife habitat.
Its free and has a load of wonderful creatures to see such as Flamingo's, Koi, Turtles and many many more.

At the Mirage you can visit the Secret Gardens and see Tigers, Lions etc, and see the beautiful Dolphins swimming around. They perform every so often when the trainers ask them to.
Worth the admission of under 20 bucks, IMO.

Over at the Bellagio the amazing Conservatory is worth a visit.
Its only a 15 minute thing, but its free and always a delight.

If you want to travel further afield other places I have visited while in Vegas, and loved are Bryce Canyon, Zion National Park, Yosemite and of course the Grand Canyon.
All of those are day trip though, so probably not what your wanting.

Enjoy whatever you decide to do.

There is much more to Vegas than gambling, drinking and sex. (Although those three things aint to bad, are they...LOL.)

 
VOF photo below. Look at those amazing colours

There are lots of places close to Vegas that you can go to.  Red Rock Canyon, the Valley of Fire,  and Lake Mead are close by.  In town the Spring Preserve is real neat.  There are all sorts of parks close by, the park on Sunset and Eastern is huge and has a nice walking trail  I found some more parks last year one if which is the Exploration Peak Park Mountains Edge  9600 S Buffalo Drive.  I've enjoyed the Vegas Wash and the Henderson Bird Viewing Preserve for years.  If you have any ? PM me.  I know of lots of more places as well.

For a quick fix on the Strip....

Try the Bellagio exhibit. It changes 4-5 times a year and they have a Holland/Spring theme right now with tulips and hyacinth and a butterfly habitat. It's beautiful, it's free and it's a good nature fix if tourists don't bother you too much.... I usually offer to take pics .

I thank you all so much for giving me some ideas on finding nature and landscape here in Vegas. While the Casinos are impressive and beautiful, mind-blowing luxury in fact, there is this natural side of me that needs simple landscape and nature. I think a nice balance of luxury, and wild nature really does the heart and soul good. You can be sure Ill be working my way down your lists. I can't wait Thankyou Thankyou so much