Of course it's your trip but going up to the dam from PG and then back down again just seems off to me. Lots of backtracking over that route.....
Just a suggestion...Edmonton to Hinton. Hinton to Grande Prairie. GP to Ft St John. FSJ to Hudson Hope (and the dam). Very nice road, highway 29 BTW, from FSJ to Hudson Hope and then Chetwynd. Chetwynd to PG with a side trip into my awesome home town of Mackenzie. Really the jewel of the north IMO
You get to see some great scenery....both the Bennet and Peace Canyon dams...and NO backtracking!!!