I thought I read on Rick RIordan's blog that the book was going to be a little over two-hundredish pages. On amazone, amazon it says 544 pages. Does anyone know which is correct?

Definitely 564 pages. It was probably a typo ou something. The Lost Hero was over 500 pages so this one will be too.

No one knows for sure as far as I know, but the plus pages in a PJO book the better

I heard that RR thinks that TLH will be one of his longest livres and he would like to make the rest a little shorter (so we won't go crazy waiting). So my guess would be around ou above 400 pages. Also, book store websites that I've looked at say between 380-440 pages so... yeah.

Source: RR's Blog