I totally agree about the Quilters Select mat. Alex Anderson was demonstrating her new rotary cutter at Paducah, and I bought it, a mat, and the 6 x 12 ruler. Best purchase ever! I was so frustrated with my ruler slipping, but with this combination, it hasn't slipped a single time. Watch her videos where she explains how the mat is slightly sticky (but not that you'd notice) so the fabric doesn't budge.
http://quiltersselect.com/products/
BTW, I thought the cutter may be too heavy, but its extra heft means you don't have to push as hard, and with its magnet closure, it's so easy to change blades.