Hi ya'll!
I attained a Media Press Pass for two Rodeos (Cody & Cheyenne) while on my trip to Wyoming. I mainly used Canon's 70-200 F4. I left the 300mm 2.8 behind as it was too big and bulky for all day walking around. Anyway, I had a great time, met some terrific people, saw beautiful scenery & and some awesome wildlife - including wild mustangs and bears. - photos coming soon.
The 70-200 produced some amazingly sharp images - its great for 'walking around all day' - when there is plenty of light. Of course for low light conditions/action you'll be better off with the 2.8 version. Overall, I am very pleased with the quality of images from the 70-200 F4 lens.
Here are some Rodeo images.
Canon 10D, 70-200 F4
Kathy