If your child is in school and you need kid books, head to the school library. If not, or *gasp* you want books for yourself, then you'll be heading to the bookstore.
I miss our great lending libraries back home.
So what are your options here?
National Bookstore (Glorietta). A chain that has a little bit of everything from art supplies to books to gift wrapping to kid games to pens to party balloons. If you're looking for a specific book though, good luck. The shelves seem to be randomly stocked and the store is generally haphazard and your best bet is to scan through the bargain bins for something that looks interesting. Unless you want a travel guide to Disney. There are many different versions to choose from.
Goodwill (Glorietta). If you're looking for cheap books this is -the- place to go from my experience. Again, you can't find anything you're specifically looking for, but one floor is all children's books (for young kids they are generally <$2), another floor is textbooks and another is paperbacks/hardbacks for the rest of us. A wonderful store to wander the aisles and see what catches your eye because as opposed to National, the shelves are orderly and you don't feel like the pages are going to collapse on top of you.
Power Books (Glorietta). An offshoot of Tower Records, the book section is small, but they have an interesting section of Filipino children's stories.
Power Books (Greenbelt). Two floors of books. Again, you can't find anything you're specifically looking for (most of the shelves are ordered by book title, kind of by subject) but if you like perusing shelves, it's a pleasant store to wander through.
Fully Booked (Powerplant). True to it's name, everything is on their shelves, they have an extensive children's section and cooking section and their employees are knowledgable about what they have or how they can find out. It's our favorite place to buy books.
Then there's always Amazon.com.