This is harder than it should be.
I think I'd like to dive into Percy Jackson's world. Except maybe instead of Camp Half-Blood, I'd go to the Roman camp (Camp Jupiter) because I find it easier to use Latin names for the gods.
Lemony Snicket a Series of Unfortunate Events has always been a dream for me when I was younger, though I don't think I'd particularly like being chased down by Count Olaf, but the many different caretakers are all so interesting. While I'm certainly not as young as I was (eleven) anymore, I would still check out Ferryport Landing from the Sisters Grimm series because I used to adore those books.