I think coming up with a title must be akin to writing poetry. You have only a very few words, and every word has to be the perfect word. For a novelist who is used to a long yarn, this is not easy.
I started out loving THE EMPYREAN CHRONICLES, but it turns out I'm the only one who loves it. I'm mulling over titles like HEAVEN'S BRINK, THE STAR CHASERS, THE SKY CHASERS... oh the list goes on. I'm not sure if I can hold out for the one title that everyone jumps at screaming, "Yes! That's the one!" because that could take years, and we don't have years. We have a week at the most, because my publisher has to start rolling it out, putting it on lists and posters and promotional materials, pitching me to conferences, etc... They need a title to do all this.
I think my problem is that I send out books with "working titles." This basically means that the title isn't good enough, I know it's not good enough, but I assume my publisher won't really like any title I come up with because they almost never do and so I don't invest too much in the title I submit with. I think this may have been a mistake, and it's one I'm going to try to learn from. Even a working title should have the potential to be the perfect title. Sure, there's a chance the publisher will change it anyway, but that's no reason not to try your best before you submit.
Writers (mostly) know how to write books, publishers (hopefully) know how to sell them. Writers are supposed to be good with words, but publishers know the market. I think most book titles are the result of much debate and compromise, and my series will be no exception. Stay tuned!