With regard to Antelope Canyons, skip the guides and just drive there yourself. The people who take your money will charge you an extra $5 for the Navajo Reservation permit and handle it right at the sites.

I would also recommend Lower Antelope over Upper Antelope. The scale is smaller and more intimate and IMO, the light and shapes are _much_ more appealing than in Upper Antelope. I also don't like the idea of having to pay an extra $5 for each hour beyond the first that I spend in Upper Antelope especially since the fee for Lower Antelope is good for as long as you want to stay (typically 3-4 hours, in my case).