Las Vegas - Which lens should I rent to play with?

I'm going to Las Vegas in July & will be doing more city photography i.e. signs, buildings.

I will be taking my 16-35L, 24-70L & 70-200L & I'm shooting with a Canon 7D. I took these in January & had fun shooting (http://www.dougsturges​s.com/domestic/las-vegas/).

Does anyone have a good suggestion about a fun lens to rent & experiment with for this trip? I was thinking about a fisheye lens...never used one but thought the effect could get some interesting shots. Any other lenses? I would like to stick with lenses that are know for their sharpness & excellent optical qualities.

Thanks for your suggestions ahead of time.

I took my 10-20 sigma, you seem to have it all covered other than a fish or super wide.