Here's a little edit from from yesterday's mountain bike ride with Maja out at Prescott's Granite Dells playground. The riding is slow going and techy but the granite surface is as grippy a surface as you can find and it's a great location for a pup ride as the trail sticks close to Willow Lake so there're ample opportunities for a cool down. A lot of people think you need a big bike for this kind of terrain but I'm partial to my little Niner Air 9 RDO hardtail as I like small and maneuverable over these big rocks. I run really low pressures as well, around 16 & 17 PSI on my Stan's Valor wheels. More grip = more fun!
If you're interested in checking out the trail, here's the ride on Strava. I enjoy this area equally on wheels or foot.