The book store might close by 6pm, I'd call first.
You could go up to the Universal city walk it's right off Lankershim and the Hollywood Fwy. It costs to park but the city walk has a lot of places to eat.
Or? go to Bob's Bigboy at Pass ave. and Riverside Dr. and have a burger and a chocolate coke, and get a side of blue cheez dressing to dip you fries in.
Then you could head over to Hollywood Blvd or the Sunset Strip
Get a tatoo for a sovenir.
Lot's of stuff to do around there.