On the Children's Shelf: Your Recommendations

I love sharing books we enjoy. I love when others ask me to recommend a book or tell me they read one we recommended. I love receiving book recommendations and I'm hoping you will share your favorites with me.
What I am looking for:
* preferably a series
* something different (see what we read/loved below)
* 2nd to 5th grade age range
We already have:
* The Magic Treehouse
* The Box Car Children
* Nancy Drew
* Captain Underpants
* Diary of a Wimpy Kid
We love Harry Potter and Keeper of the Lost Cities, so anything with a similar would be awesome. I want to introduce new books into our house this year, and I want the younger reader to have options that aren't just the same ones the older readers have already read. Any recommendations appreciated!
Happy New Year of Reading!


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