Hmmm...that choice of lenses does give you a tough choice, doesn't it. I should mention that because at Dartmouth all the displays take place right over the river things are a LOT closer than they are at most shows.
Shot two is uncropped from the original image and according to the image file was shot at 190mm, no. 6 (the close pass) was cropped a little, and was at 168mm (Camera's crop factor is 1.6x)........a lot of the time I was only working a little above the 200mm level......I'd be inclined to start with the 70-200mm lens on the basis that a better quality lens will deliver you sharper results anyway and you may be able to crop to a good image - you can always change after the first display or two if you feel you want a little more reach.
Whatever you decide - have fun and remember to share the results!!