Hwy 49 above Nevada City is great fun. Working your way through the canyons of the Yuba on the way up is part of the fun. Downieville is a good place to stop and look around and top up your gas tank. Be aware that speed enforcement is more common as you approach Downieville, and it can remain that way to up above Sierra City.
Continuing on Hwy 49 will take you over Yuba Pass, which is very entertaining, then intersect with Hwy 89, leaving your the choice of going south to Truckee or north to Quincy. The alternative to this is to turn north at Bassetts on Gold Lake Hwy, a very scenic road that comes down to join 89 near the resort town of Graeagle.
One of the benefits of Yuba Pass compared the the passes further south is that it's further from major population centers, thus is less likely to be crowded. Make a loop with the Hwy 162 / Oroville - Quincy Road or with LaPorte Road for a really fun day.
Nice and very twisty section through the Tahoe forest, great selection of corners and nice surroundings