Space needle---no problem.
Willis Tower---no problem.
Empire State Building---no problem.
The Eiffel Tower (Las Vegas version)---BIG problem
Nice view of the strip, but my acrophobia nearly paralyzed me within seconds of stepping out of the elevator. There was limited walking space and I could've sworn I felt the whole thing sway. After enjoying the view for a split second, I stepped into the line that led back to the elevator. Unfortunately, this line wrapped around the entire observation area...so whether I liked it or not, I was stuck there.
The next time I nearly pass out thousands of feet above ground, I rather it be on The Eiffel Tower (Paris version.)