If you are a wine enthusiast, I would note that the wines served in the dining car--all Canadian, of course--are B list wines. But those served in the Park Car are a cut above. It wasn't till our second day that we discovered that you can ask for the Park Car wines in the dining car instead of the 'standard' dining car wines. Don't bother bringing snacks or drinks along, unless you have particular dietary requirements--in prestige class, they constantly make food and snacks available. (Maybe think about wearing elasticated pants??)
Bring a nice eyeshade for sleeping, since in June you will have maximum daylight. I have one that has cups in it so that the eyeshade doesn't press on your eyes--it makes wearing it more comfortable.
It was our experience that tipping was both less expected and when tipping, the 'standard' amounts were lower than on Amtrak. Do whatever you think appropriate. But be aware that the onboard passenger crew changes out at Winnipeg, so if you plan to tip your sleeping car attendant, the Park Car attendant, etc. you'll want to do so before the Winnipeg stop.
We purchased two paperback rail guides prior to the trip, and I can heartily recommend both for their coverage of the Canadian and what you'll see along the way: Canada by Train, 3rd edition, published by Way of the Rail Publishing,
www.wayof therail.com. Also Canadian Rail Travel Guide by Daryl T. Adair. I don't have any idea whether either or both have a recent edition, but the general information about the route and sights, as well as background of Via Rail and Canadian rail travel, are probably useful even if they haven't been updated. Both cover Canadian trains in addition to the Canadian, but as you might guess, that train gets lots of coverage. According to Amazon, both seem to be still available, together with another guide written in 2000. I've always said that travel guides are a miniscule part of a travel budget and provide information so you get the most from the trip.
One of the advantages of having detailed route guides is that you can anticipate good photo ops in advance. And speaking of photo ops, at least when we took the Canadian, the Park Car was on the very back of the consist, meaning that you could take advantage of the railfan window at the back of the Park Car for photography. Although the trains' windows got washed before we hit Jasper, Canadian insects seem to find train windows irresistable. Splatted bugs are the enemy of photos. But, given the position of the railfan window, it was clear of bug debris the entire journey.
The bed in the prestige cars is a true double bed--no clambering up a bunk!--that is a Murphy bed brought down from the wall. Very comfortable for sleeping for two, but when it is down, it blocks access to some of the cubbies and storage in the room. So take care before your room is made up for sleeping that you have glasses, reading matter, phones, hearing aids, etc. that you might not want inaccessible for the night. Ask me how I learned this...
The in-room bathroom is much more spacious and nice than what you'd find on an Amtrak sleeper. The shower in particular was both roomier and had better water pressure, and they supply high end toiletries and a hairdryer, too!
There are a number of scheduled activities on the train, but I cannot speak to them since we spent all of our time in our room or the dining room or the Park Car. But your sleeping car attendant--more of a concierge, actually--can let you know what is scheduled so you can decide to partake or not.
I can tell you that a trip on the Canadian, especially in prestige class, is an absolute bucket list experience!