For some good pix of Prince George's staple backyard whitewater run, the Willow River, check out this link. Lower Willow.
Isle Pierre, Nechako River
The Nechako River is a long meandering class I river, but in a few sections there are some rapids. Isle Pierre, located about 40 minutes west of town is one of them.
The picture above is Jess Rayner in the middle of the main rapid. This run is great for beginners looking to get a feel for big water, as there's a lot of volume pushing through, which creates some fun whirlies and boils. There's also easy options for going around the main rapid for the less brave/experienced.
The Bowron is best earlier in the season when levels are high. Located about 30 minutes east of town, it has a couple different runs: (1) the Boulder Run, located just upstream of the Highway Bridge; and (2) Portage Canyon found further downstream.