Budget more than you might expect for Canada. This summer the exchange rate was basically 1 to 1. Food a drink were very expensive compared to Montana. We saw a 12 pack of Molson going for $20 in Pincher Creek. We ate dinner out in Sparwood and two salads, fish & chips and a double cheeseburger with fries set us back a little over $40. On the subject of Sparwood, a stop at the truck is a must. There is also a grocery store chain called Overweightea that has good things for lunch. You will have to Google the name to learn its origin. Note that our cards did not work in kiosk-type ATM's at two convenience stores in Fernie. But they did work at ATMs at banks.
Stop at the cafe in Coleman for a cup of coffee or lunch. It's a former church with an inviting decor. You won't want to leave.
Eat a good breakfast in Waterton Village. Not long after you leave the park entrance, where P.R. 5 and P.R. 6 split, you will come fact to face with a monster climb. Not only is it physically challenging, it gets you psychologically because much of it is straight so you can see what's coming the entire time.
Definitely take the "side roads" used by the AC route between Whitefish and Eureka. Not only do they get you off U.S. 93, the riding is serene. Take the time to go the half mile off U.S. 93 into Olney. Brigg's Merchantile (the only store between Whitefish and Fortine) is quite interesting. Great collection of old pop bottles.
You will want wider tires for GTS. You will also want them for Belton Stage/Blankenship Rd. between West Glacier and Whitefish.
Finally, if you will be flying to Whitefish, consider UPS-ing you bikes to Glacier Cyclery. Great group of people, and they will store your box for you.