Ok this is the PLACE to use HDR shooting techniques and then layering the shots.
In one of the antelopes you actually just walk right up to the rock face that the caynon comes out of, the other and more dangerous one you have to go down ladders into it (I have never gone into the second one). So you ride a vehicle in, at one time you could take and old WWII DUCK in, up the wash where the canyon gets wide and the walls are just sloped sand up to the rock face that is over 40 ft high and walk into the first chamber of the canyon. The floor is sand the whole way, I would say that it is a medium grit beach type sand since it washes into the canyon everytime it rains since this one slot is the drainage for several hundred thousand acres to go into Lake Powell that is north a few miles away. Just think of a long Mesa with a crack in it so the water escapes through this crack. So all sorts of debri can get caught up in the upper reaches of the canyon above your heads, some stays just till the next big rain further up the basin while some stays for a year or two (ie trees mostly). Now the difference between this canyon and the other is that if water comes in you can head back out along with the water flow to where it opens up while in the other you end up having to go against the water to get back to the ladder that you entered in or try to outrun it as it approaches the lake-unless they have added ladders on the low end.
THIS IS A TRIPOD NECESSARY AREA, the best shots that I did (this was all film-most slide 64asa) were 5 minutes and longer in duration-don't push your camera speed extend the exposure!
So if you walk into someones shot just keep moving in most cases you won't show up in their shot unless a light beam catches you dead on. You can actually do some interesting things with friends in there but no artistic "stuff" unless you pay for a commercial shoot permit and you usually can't be there at the busiest times since the revenue is higher from 50 people than what you would pay.
One thing bad about going in the off season is that the sun isn't right above so tough to get some of the better lighting shots. Now I've never seen snow shots with snow in the canyon but I bet those could be real cool.
On the other end of the canyon you can actually climb pretty easy to the top of the mesa and look down into the canyon but there isn't really a whole lot to see other than darkness.
Navajo Parks & Recreation - Antelope Canyon
To see the topography just go to google and put in Page Az then pull up the satellite images, look for the power plant to the east of town and the canyons are nearby. There are other slots in the area but they are on private land and I have yet to see one that is bigger than Antelope.