The Cassiar Highway is well worth the drive. See my page at
http://suethomas.ca/CassiarHwy.html for dozens of pictures of the whole route.
The section between Dease Lake and the Yukon border can be rough and it is narrower, but it is entirely do-able. Last year I drove the F-250 pulling a 24' flatdeck car trailer loaded with household goods through this section in two hours; wasn't going fast anywhere but managed in fine form.
We've towed our 25' fifth wheel through many times too.
Our preference is for the Cassiar. The Alaska Highway is so much busier and hectic, while the Cassiar is quieter.
The bears will also be out, making for good wildlife viewing.
