Is it difficult once arriving at Union Station to find where we need to be for the tour?
I was looking for this myself and found the following information from GrayLine:
To get to the bus level, you will go to the center rear of Union Station and go up an escalator, then out the doors leading to the parking garage. Just outside those doors is a second escalator and elevator and we are located on the first level up on the left, next to the Greyhound office.
Hope this helps!