And by turn around, it makes a big loop around at the top, so the sides are switched once the loop is completed. We did the round trip with my mom in 2022. Last time was around 2007, when they moved the engine (after telling everyone not to leave the train, due to the switch being in Canada). They did ask everyone to switch sides.
Good plan, but the Waterfront station is a few blocks away from the Marriott. It's a bit of a walk with luggage. The cab fares are regulated, I think.