I have ridden the White Pass & Yukon RR and I believe it's worth the money. I am a railroad fan, so almost every train ride is worth the fare.
There's many tours to the Menddenhall Glacier, which one are you planning on taking? While I didn't take the whale watching tour, I've heard it was great. If there's whales nearby, you'll get up close to them.
Have a great Alaskan cruise.