Are you looking for a bargain? This is not your place.
Are you looking for an amazing once in a lifetime vantage point? This could be your thing!
We visited on a recent trip to Toronto and it was truly incredible. I am scared of heights but the view is so wonderful that I just ended up taking it all in and found it incredible! The elevator ride is fast enough that you can't even believe that you have ascended 131 floors already.
I don't imagine that there would be any reason to visit CN tower more than once but it is definitely worth one trip! It is pricy for an attraction that doesn't last too long but I understand why they have to charge so much. They also offer a CAA/ AAA discount, just ask and show your card.
*quick tip- it gets BUSY around 11am and the people can really impede your enjoyment (it gets FULL on the glass floor and you can't even get in there to take pictures or enjoy it). Go early!