Hi Jan
I did the earlier version of this JY tour back in 2011 and loved it - in fact, until Alaska topped it last year, it was my all time favourite JY adventure. You will have an amazing time.
If you put 'Rocky Mountaineer' into the search function on the top right of the page, you will find reviews, hints and tips from other JYers who have done it.
My advice - pack layers (cold in the mountains, warm on the coast), take double the amount of memory cards you were planning on (and batteries) and, if you can, upgrade to Gold Leaf - it's pricey but, as a one-in-a-lifetime treat, totally worth it.
Happy to answer any other questions
All the best
Mandy