I just purchased the toursaver for this very reason. I taked to them at Talkeetna Aero befor purchasing though. We want to do the Summit flight and that one is a bit more. She said you can use the coupon 2 for one with a $20 upgrade to the Summit flight. It works out to be $122.50 after applying the coupon. The book is $99.95 so even if that's the only thing you use it for, you're right...it's a no-brainer in my opinion! We'll be using it as much as possible, so every other use makes it that more of a savings!
Have a wonderful trip to Alaska!