I'm planning on making the trip later this summer.
My wife and I made the Alaska trip a couple of years ago and I thoroughly enjoyed it. But there is so much to see and do in Alaska and on the route to there, that I'm planning on making the trip again. My wife is having to take care of her aged parents, so she is not able to make the trip again.
Have you done much thinking of what you want to see/do while en route? I'm planning on heading out from my home base in Texas in early July. I have a vacation condo in southern Colorado and I want to be there for the fourth of July. After the fourth, I plan on heading to the Canadian border and will spend a week in Banff/Jasper. From there, I'm planning on heading west out of Jasper and will take the Cassiar north. There are several side places that I want to see off of the Cassiar, mainly Prince Rupart, Stewart, and Haynes. The Cassiar tends to have more wild life, but is also more desolate. Also since a lot of the service stations on the Cassiar will shut down in September, I want to take it earlier in the season.
Before reaching Whitehorse, I'm planning on a side trip down to Skagway. Whitehorse is nice, but it is mainly a place to stock up. There is a Walmart and a rather large Canadian Tire there. From Whitehorse, I'm planning on heading north to Dawson City. After a few days in Dawson, I'm planning on taking the "Top of the World" road over to Chicken or Tok. All in all, I suspect that I won't arrive in Alaska until August.
One of my main goals on this trip is to see the Aurora. On our last trip, we had to leave early because my in-laws had some serious health issues. We started heading back in early August and that is too early to see the Aurora. My guess is that I won't be able to see the Aurora until late August or early September. That means that I'll need to plan on returning on the Alaska Highway because there are more services on the Alaska Highway than the Cassiar. Also once the fireweed turns white, you're only a couple of weeks from heavy snows.
The only disadvantages of going up the Cassiar and down the Alcan is that you don't get to take a dip in Ilard hot springs until on the way back and you reach the famous mile zero sign in Dawson Creek at the end of the trip instead of the beginning.