New Project - Playmat Blanket

I'm starting a new project. One that I'm sure that will last me a long time. I'm going to start the Playmat by Debbie Abrahams from 100 More Afghan Squares to Knit More Blankets and Throws. It calls for Rowan All Seasons Cotton but I'm using Debbie Bliss Stella yarn in:
Pink x 6 skeins
Teal x 7 skeins
Fuschia x 1 skein
Magenta x 6 skeins
Lemon x 6 skeins
Ecru x 2 skeins
I found each skein of yarn from Jimmy Beans Wool for $3.75/skein (half-off the original price of $7.50). I can't imagine using a more expensive yarn since the total for the half priced skeins was $105 (with no sales tax and free shipping!) This could be one expensive blanket!
The Debbie Bliss Stella yarn is an aran weight 60% silk/20% rayon/20% cotton blend. If I was going to spend all of this time making a blanket I wanted it to be a luxurious one. I've heard a couple complaints that it's a semi-splitty yarn but hopefully it won't be a problem once I get started.
The blanket consists 20 different patterned boxes that make up the 49 boxes that need to be made for the blanket. The blanket is 7 squares by 7 squares. I was thinking that I would make the blanket in strips and mattress stitch the strips together instead of casting on and casting off each individual square and seaming them all together at the end. Hopefully it will cut down on the seaming and make the blanket look a little smoother. From what I can tell all of the squares start with the same number of cast on stitches which makes it super simple.
I'm starting tonight and will keep you posted on the results...