After finishing the Lewis Barnavelt books, I read The Last Star by Linda McNabb. It was a bit weird, but very interesting with a lot of twists and turns that I did not expect (and dragons!). The ending was surprising, and a bit disappointing/bittersweet, but with the way the rest of the story had developed, there really was no better way to end it, so while I wasn't thrilled with how it ended, I can accept it as the best possible outcome given the circumstances.
Moving on from there, I've started The Dead Gentleman by Matthew Cody. It's more of a steampunk/sci-fi type story, but still an enjoyable adventure. I've read it once before, and if I remember correctly, it had a sort of non-ending like there was supposed to be a sequel, but it's been a few years, and Matthew Cody has written (at least) two more books, but none of them have anything to do with this one. I'll look him up and see if there's anything going on with this story.