Shutterfly actually offers 2 different layflat options. I think the one Jacinda posted about, with thicker pages, is like their deluxe layflat. I love it, but I don't love the upcharge. I usually get the middle Shutterfly option, the standard layflat pages. The binding style is different so that the pages lay much flatter than in the regular photobooks, but the paper isn't thicker.
Here are pictures of them. The regular one doesn't stay open on its own--I had to hold the pages down to even take a picture, and you can see how much of the pages are somewhat in the gutter. Nothing important got cut off, but I purposely kept everything away from the gutter area when I scrapped the layouts. There is a definite valley that some of the page falls into, and I think it's a little more obvious in person than in the photo. I do buy this kind for small, inexpensive photobooks, like when I'm printing an 8x8 vacation album with only 20 pages. It's not terrible, but if money was no object I'd always print layflat.
This is the standard layflat. I'm not holding the pages--it stays open like this. There's a slight curve, but I don't notice it unless I'm comparing it against the thicker pages like I am in the bottom photo. This is my go to for our annual photobooks.
Here are the regular, standard layflat, and deluxe layflat. Even though they're stacked up here, this is exactly how each one looks when they're not stacked, too--the weight of top books isn't holding the lower books open. (Fair disclosure--I assume the bottom one is what's now considered deluxe layflat. I bought it right after Shutterfly started offering layflat pages, and at the time it was the only option. The pages are thicker and lay perfectly flat, but the book is a lot wider than on the standard layflat.)
