Savitch's book is superb as a textbook. You won't find many other books that are that good.
The two things I'd suggest learning about are data structures/algorithms and design patterns.
For the former, there are a lot of text books, but the good ones are advanced and expensive (for instance, Cormen, Leiserson & Rivest, *Introduction to Algorithms*), and the inexpensive ones are poorly written. You might try the O'Reilly book "Algorithms in a Nutshell*.
For the latter, there are a number of books - a good intro book is *Head First Design Patterns*; the book of books is the so-called Gang of Four book that introduced the idea, *Design Patterns* by Gamma, Helm, Johnson, and Vlissides.