Early dinner (or filling snack) near Book Soup?
Ketchup if you don't mind going when they open at 6pm. At least they probably won't be very crowded, so service should be fast. Fairly new place - search on here for some recent reviews. Recommend not having a full dinner - just order from their apps & drinks menus. The tacos and the french fries are great. Very cool hip ambience.
If you don't care much for ambience and want more food for your money, there's a Mel's Drive-In up there on Sunset and also the Rainbow Bar & Grill which is pretty good. And Carney's for great chili burgers and chili fries and you get to eat inside an old train car or something...
I hate to be sen saying this, but I actually like Mel's. OK the food isn't spectacular. But it's pretty good. Valet Parking is free, an oddity on the strip. The shakes, malts, and pies are pretty basic, but good.
Sometimes, I just hanker for medicore fake-diner food. Usually late at night.
I also like sitting and drinking a malt and eating apple pie whilst watching cruisers, club kids, and tourists.