In June 2005, a group of us rode from fairbanks to Vancouver and took the Cassiar - at my suggestion because I was intrigued by the nickname "Bear Alley." Go to www.redwingaquatics.com
for the daily mileage, overnight accommodations, pictures, etc..
It is definitely more remote, but there is only one stretch where you have to go 100 miles between overnights stops. Extremely picturesque. There are plenty of interesting sites and experiences.
In July, you will have tons of traffic on the Yellowhead highway with cars and logging trucks. Once you turn onto the Cassiar, you will have some logging trucks, some commercial trucks, and a fair number of RVs. There is very little flat road for you to travel - they did not spend money to flatten the road and it follows the terrain more than anything else.
There are a couple of sections that are very steep for 5-6 miles and you think you are gonna die. You will also encounter 50-75 miles of unpaved road as well as deep gravel in some spots. All passable - just slows you down.
By July, I don't think you will have to worry about bears. And, depending on the rain, you will have your share of misquitoes to deal with. I found that 100% deet worked ok.
Read the blogs I mentioned above and write back if you have any questions. Also, get a copy of The Milepost (library or on-line). It details just about every mile of the trip you are taking. Only problem is there were some campsites they said were open and were not.