Another suggestion if you have not been would be to stop in Arches National Park in Utah, there is some beautifully sculpted sandstone landscapes and some nice and simple day hikes. Also, Meteor Crater if you have never been there. It is quite a sight to see the crater and realize that a rock 50 meters across made the hole that you are looking at. Absolutely amazing!!!
Another cool visit, not quite geological but manmade, is Montezuma's Castle. It is amazing to see the abilities of some of the ancient people when building structures confined to cliff edges. Great thing to visit.
If you are willing to make a long hike, Havasupai (which is thirteen miles long) offers a great way to explore one of the side canyons off the GC. Contained within this hike is a lot of desert landscape and then a scrub brushish forest. Once in the campground at the bottom you are within simple walking distance of three amazing waterfalls. Havasu Falls is about 100-150 feet in height and has some cool boulders near the falls to jump off of into the pool, Moonie falls is about 250 feet in height and has a small little cave behind the falls and Apache Falls is a very secluded portion of falls with a legend that the Apache chief refused to surrender at the top of the falls and the Havasupai chief stabbed him and threw him down the falls. Just a great experience there.
I will try and think of some other suggestions for you as well.
The theory of evolution by cumulative natural selection is the only theory we know of that is in principle capable of explaining the existence of organized complexity. - Richard Dawkins
Creationists make it sound as though a 'theory' is something you dreamt up after being drunk all night. - Issac Asimov
If you removed all the arteries, veins, & capillaries from a person’s body, and tied them end-to-end…the person will die. - Neil Degrasse Tyson
What would Buddha do? Nothing! What does the Buddhist terrorist do? Goes into the middle of the street, takes the gas, *pfft*, Self-Barbecue. The Christian and the Muslim on either side are yelling, "What the Fuck are you doing?" The Buddhist says, "Making you deal with your shit. - Robin Williams