I've done several of the roads in the area; one of the nicest drives is to go north from Princeton through Coalmont and Tulameen, continuing north along Otter Valley Road for several miles traversing lands belonging to the Douglas lake Ranch. At the junction of Otter Valley Road and Brookmere Road you turn west and follow the old Kettle Valley Railroad route passing several old train stops all but forgotten now. Eventually you cross over the mountain divide and descend into the Coquihalla Valley and arrive at Brookmere, which is the old KVR subdivision stop. From there it's an easy drive downhill to the Coquihalla Highway.
If anyone is interested in a trip report and pictures from the route I just mentioned you can read it here
Scroll down the page until you see the story titled "Hope to Pricenton to the Coquihalla"