Don't take the tours from town. If you have rented a car, drive out to the slot canyons and enlist an Indian guide. They are very knowledgeable about the best photo spots and about camera settings and light in the canyons. If you're not a absolute pro, take their advice. You won't be sorry.
Lower and Upper Antelope Canyons are located a short distance from Page, AZ. Lower Antelope Canyon is the longer of the two and has a surprise at every turn. There are many tight spaces and ladders to negotiate in Lower Antelope Canyon. Upper Antelope Canyon is much shorter and is fairly flat.