If you look on the site they list all the excursions that are available. You only have to do one glacier tour and you will have paid for the book. We recommend the Stan Stephens tour out of Valdez. In Fairbanks the river boat tour is great.
We didn't make reservations during our trip except for July 4 weekend and Denali's Teklanika campground. We had no problems with getting on the tours we selected by calling a week ahead when we could better judge where we would be.
I'd advise getting the book unless you can't find anything in it that appeals to you. We're not tour folks but both of the above are a must for your Alaskan trip.