Gee, that was just about the exact opposite of my experience there.
Some things that I found that really helped my experience.
1. 12-24mm on a full frame? It sounds like you were shooting too wide. I had my best results with focal lengths of 35mm and above. This really helps to isolate the formations without the distractions of people walking thru your shot. My buddy shot with a 70-200 the entire time he was in Antelope. Sometimes it pays to be counter intuitive.
2. 30 second exposures? My longest exposure was about 8 seconds. A lot of the time I was shooting exposures of 1 second or less. Even on one of the famous "sandfalls", I only had an 1/2 sec (@ f/14 and ISO 320). You can't reasonably expect to have 30 seconds to yourself in that place.
3. All it took to clean my lenses while I was there was my rocket blower. Honestly, dust should only be a problem if you're shooting at the smallest apertures, which given the size of antelope canyon, really isn't necessary.
4. People flock to Upper antelope to shoot the cliche and overdone "light beams". These only happen during the middle of the day, so OF COURSE it's going to be crowded at those times. If you show up at some other time, then you can get some unique shots and you aren't battling the crowds.
5. I would have been happen there even if I hadn't taken a single photograph. It's a magical place.
6. Finally, it's Navajo
, not Navahoe. In fact, Navahoe is slang for a native american whore and pretty disrespectful. The simple fact that you got this wrong, shows that you have very little respect for the people or their culture. If you understood their history and realized how badly the white man screwed them over, you would begrudge them making a little money on one of the few things of value that the white man left them. Drive around on the Navajo reservation for awhile and see the abject poverty that these people live in and then reassess the inconveniences you were faced with trying to take a few pictures...