At the elementary levels, I'd recommend the textbook and "Challenging Word Problems" books, especially the newly revised versions which seem better to me than the ones available a year ago. The textbooks include the instruction as well as a fair number of practice and review problem sections. The textbook problems are targeted at exercising the learned material, and the workbooks are mostly more of the same, while the CWP includes some problems which are a bit more complex. Their website has sample pages of everything to get sense of the content. We're still in the elementary books, so I don't yet have experience with the grade 7+ books.
