While on business in Toronto, I made it a point to get to the top of the CN Tower. Yes, it is touristy, but hey, I was one so I felt ok about it...
Luckily, I went during the work week and it wasn't busy at all. I barely waited in any line and before I knew it I was atop the tower. Like many tall buildings in big cities, the views were cool.
The hilight for me was stepping onto the plexiglas floor and looking straight down. I will say the Sears Tower in Chicago has it beat though. There, you step into a plexiglas box that actually hangs off the building. Now, that was truly amazing.
All in all, I certainly enjoyed myself.