NoveList is a genius service that DC Public Library provides to you, for free, with your DC Public Library or DC One Card. Know your favorite book? Put it in the search box, and it will suggest books similar to it that you might enjoy. Just know you're in the mood for an adventure? It'll recommend choices for you that are good fits for your age.
These documents compile book suggestions that I've given to students and families over the years. They are both too long and much too short! There is overlap between grades; for example, many of the books on the first grade list would still be enjoyable to second graders. I would recommend looking at neighboring grades.