DON'T ever turn them back in......You will get a terrible exchange, either save them for your next trip.....OR if you are on a cruise, use them for extra tips for the service.
We just walked from the end of the cars to the Glacier in July....Layers, we had a very warm day, lots of people in shorts....It is a walk that takes about 40 minutes from the end where the Trollcars stop. Need good walking shoes.
While we have stayed other places I like better, The Marriott is by the museums, plenty of restaurants, has self laundry...which did come in handy...and has a wonderful breakfast.
Much as I love Viking...over the past few years their payment policy has become..well odious....Explore other options, other lines.....Viking does this because they can.
We had first class tickets on this train......UNFORTUNATELY we had to lug our heavy suitcases up a spital staircase to the top level......Never been in first class and had to go upstairs.....We are usually down with our luggage in sight....We do cable several bags together.
The bottom of the hill is the last place anyone can park cars......It probably took about 25 minutes to reach the top....strolling along, window shopping....We had a wine, cheese, lunch at the top of the village with awesome views.
It is definitely a fair piece up the hill....and it is steep in a lot of places.....we had to park at the bottom as well and went up to the top with our guide.
You picked a better cruise for the month of August....It still will be crowded, but the area you are in the weather will be better....It is an amazing itinerary...ENJOY