I see a picture of Marble Canyon Lodge taken from the Maule. The runway is about ten feet wide, maybe a little wider, and it's really a one-way airstrip from which a go-around may, or may not be possible. Plan accordingly. Watch out for very large, red ants that bite hard, don't set anything on the ground that you aren't willing to have absorb a snake, ants, or a scorpion. You probably won't see them, but be prepared. It's desert, and what lives in the heat seeks out the shade...including you. Some things weren't meant to share the same space.
I've gone into Cliff Dweller's Lodge (just down-canyon from Marble Canyon lodge) and marble canyon many times in 206's and 207's. Cliff Dwellers is private and a dirt airstrip, with limited facilities. Marble Canyon only has a few tie down facilities. Always carry ample water and supplies with you. Unlike many places where you might be used to having plenty of runways and airports, the west is sparse, and few and far between. You're also on the Navajo Nation reservation, ostensibly in a different country.
Never fly anywhere without a jacket, even in hot summer weather. Keep density altitude in mind. Plan for the cooler parts of the day. Don't plan on getting fuel at places like Marble Canyon or other canyon strips; it won't be there. Carry what you need to get there, and get back. Remember that weather pops up suddenly, unexpectedly, and the terrain makes it's own weather. Remember when it comes to landings that getting down and getting stopped is FAR more important than a long, floating effort to get a greaser of a landing, and that airspeed control is a very big plus. Centerline is important, especially when there's no centerline and some runways aren't much wider than your landing gear. I've landed on some throughout the region that have literally inches to spare on each side of the gear. (Sandwash in central Utah leaps to mind).
Monument Valley is now paved; it used to be half dirt, half paved, withouta smooth transition between the two. It's a one-way airstrip too. Formerly a herd of Navajo sheep and goats would cross going one way in the morning, driven by a dog, and come back in the evening. Don't be taking off or landing when that happens. I believe it's fenced now, but having critters crossing your landing path isn't unusual, so be aware. Anywhere out there is very much a heads-up see-and-avoid kind of place, so if you're in the habit of letting your radio look for traffic, don't.
The Canyon has undergone several airspace changes since 1991, so use the most current information. The canyon has it's own special Federal Avaition Regulation (SFAR) 50-2, and it's own chart. Operators who fly tours there have to pay big dollars for the privilege of simply going into the airspace (three quarters of a million dollars yearly, typically), and are authorized for certain routes and altitudes where you can't go, or shouldn't go, especially if you're not familiar. It's a spectacular place, and it's very important to remember that folks are loking at the canyon, not necessarily always for you, and a small airplane can easily disappear into the 277 mile stretch...collisions do happen there.
Monitor 121.5 everywhere you go. It may be you that hears someone else and saves them, it may be you needing to talk before you go down in terrain that doesn't allow you to get a signal out to anyone except those directly overhead. I've picked up distress calls on several occasions from river runners who've been injured at the bottom of the canyon, and it could just as easily have been me...so listen. Same for sector frequencies.
I've been down inside the meteor crater in a light airplane. I don't recommend you do that. Today they get upset and just like violating the park airspace, it can land you in a lot of trouble. Particularly since 09/11.
I've been shot on several occasions while flying in parts of the canyon that are no longer accessible. Environmentalists who were a little too militant about trying to enforce their views of keeping the airspace over the canyon free of trespassing airplanes have on occasion taken matters into their own hands. It's not unheard of for regulars to monitor certain sections of the canyon and photograph trespassers for enforcement action, so be aware of that, too. There are a lot of folks to take that airspace very seriously.
At the other end of Lake Powell is Rainbow bridge, which I believe is the largest natural arch in the world (I may have that wrong). It's a sacred site to the Navajos, on the North side of Navajo Mountain, large dome shaped mountain west of Page. A flight from there west will take you through Monument Valley, where a great many western cowboy movies have been filmed. Up to Moab and Green River will take you over a lot of country that contains petroglyphs and cliff dwells from the Freemont and Anasazi Indians, though you may have to get down low and slow to find them...take someone experienced if you elect to go that route.
File flight plans, check in often, and if you change your plans, let someone know. You can easily disappear out there, and there are a lot of places where you might not be found for years, if ever. There's little radio coverage or radar coverage at lower altitudes, so keep that in mind.
St. George UT has rental cars, and you can drive to Zion and to North Rim or even up to Bryce Canyon. You can also fly to Bryce and get a shuttle to the Canyon where you can hike the trails. It's the best way to see Bryce; it's better while hiking than from the air, and it's fairly spectacular from the air. It reminds me of a giant melting orange ice cream.
Take plenty of film or batteries for your camera. You won't stop taking pictures, where ever you go. I flew thousands of hours out there, and never got tired of it.
There's a west end place you can visit, near Quartermaster Canyon. At a place called Deadhorse point, or just northwest of there, you'll find Grand Canyon West, which is now a paved strip. The Hualapai Indians run it, as it's on their reservation. I don't know what they presently charge, but there's a landing fee, and a per person charge. They'll take you out to the edge of the canyon, and serve you a meal. They have a glass walkway that extends out over the canyon now, that allows you to walk out over the edge and look down. Be aware of a lot of VFR traffic going in and out, as well as making low west-end tours. Just at the west end is also Pearce Ferry airstrip, the oldest airstrip in the Canyon. It's dirt, remote, and has drop-offs at the end of the runway. It's no place to reject a takeoff, land long, or takeoff too heavy. It's also a great place to get a picture of you and your airplane, and a different experience if you're not used to it. Lake Mead is a pretty place to fly, too, and of course at that point you're not far from Las Vegas. You can find plenty to do there. too. I recommend if you're going to do that you plan ahead, and consider using Henderson. Plan on your head really being on a swivel; there's a LOT of traffic.
Enjoy; there's a lot to appreciate out there.