It's not easy for a watercolorist to find a good sketchbook. Sure, there's lots of excellent books with superb quality paper but they only have a few pages and cost a buncha bucks. Then there's the sketchbooks that claim to be able to handle "washes" and promptly turn to wet toilet paper with the touch of a brush.
I am a fan of Moleskine but their limited sizes and over inflated, hipster pricing is too much for me. I recently purchased a Stillman & Birn Alpha Series sketchbook in the effort to find a happy medium. I am impressed with the paper's ability to withstand watercolor washes and the minimal bleed-through. The lack of color integrity is disappointing but it is a sketchbook after all.