I have driven the Kamloops to Cache Creek to Prince George route more times then I want to think about. It is about 525 kms (325 miles) which can easily be done in one day.
If you wish to split the drive into 2 days, once north of Cache Creek, consider staying at
Lac La Hache Provincial Park just north of 100 Mile House. Alternatively,
Ten Mile Lake Provincial Park just north of Quesnel. From here, Prince George is an hour away.
Note that neither park has hookups but have have bathrooms and I also know that Ten Mile Lake has showers (for a $1.00 cost though) and require our Loonie ($1.00 coin) to pay for the showers.
If you are looking for full hookups, there are number of private campgrounds along the way but have no experience with them but others here might.
Once in Prince George, this is the last big city before venturing further north and is a good place to stock up on reasonable (for Canada) priced groceries etc. In Prince George and at the junction of Highway 97 and Highway 16 West, turn onto Highway 16 West. Just a very short distance and to the right is a Superstore (national grocery chain) Costco and other stores conglomerated in the immediate area. A few minutes further along Highway 16 West and up the hill is a Home Depot, Walmart and Canadian Tire (national home, hardware and auto store.)
