So, unlike I was told, the Glen Canyon Dam tour is not free (as opposed to the Hoover Dam tour). However, it is much cheaper - $5.00/person They started charging for in 2009 - years after my source had been there.
Here is the Website to the actual tour:
The picture below, taken from the website shows that tours last about 45 minutes.But another website says to plan on spending 1 to 2 hours (http://www.canyon-country.com/lakepowell/gcdam.htm). I will plan for 1.5 hr.
The Website also has the year-round tour schedule. The First one being always at 8:30. I might choose this one and then go back to the raft tour place for the 11:am raft tour.
Will we be able to make it to the Dam Tour? I don't know. Tour takes groups of 20 and reservations must be done and paid for in person. We won't be able to make it before the day of the event, so we will just hope there is room for us on the 8:30 when we get there at around 8:15 in the morning.