Progress on my Babette Blanket

Pattern: Babette Blanket
Designer: Kathy Merrick
Source: Interweave Crochet, Spring 2006

I started this blanket in March as a sort of ADD-friendly crochet project. Since there's about 130 squares in the blanket, I put the code for each square on a little slip of paper. That way, I figured that I could just take up the hook whenever the mood struck me, crochet a square or two or three, and add the square to the finished pile.
To assemble the blanket, you first join the squares into ten strips (which fit together log-cabin style) and then assemble the strips to each other. So far, I've crocheted about 100 of the squares.
This week, I realized that I was getting really close to having all the squares done for the first five strips, so I stopped the random-draw process, finished the few remaining squares for those strips and joined the five strips together. Here it is so far:

I reversed my usual procedure and tried to stick fairly close to the color choices that the designer used, although that ended up being a lot easier said than done. This blanket was designed using Koigu PPM which, as everyone knows who is familiar with Koigu, is created in small lots and each color is different. It's not like you can walk into a yarn store and find the full range of colors. (At least, you can't in the best store in Seattle that carries this line!) Also, there are 18 colors in this project and there were just not enough semi-solid Koigu colors that worked together in stock. I considered using some of the KPPPM (variegateds) but I didn't want to go that way. So, I bought some colors in Koigu and the rest in Shibui Sock, which is a very similar yarn.
Since I had to improvise, I just chose colors that I thought were close enough to the colors she listed, then completely substituted different colors in a few cases. For example, I couldn't find a "citron" I liked, so I went with carrot orange instead.
I wanted to go with the designer's color list because 1) I generally do not choose bright colors, and 2) I am not confident enough with my color sense to buy all that yarn on my own color choices. In all of my knitting (and crochet) I gravitate a lot more toward texture work over color. Plus, I wanted this blanket to retain the cheerful look. Might as well have at least one touch of cheerfulness untinged by sarcasm in my daily life!

The big question mark for me was what method to use to join the squares. I don't have much crochet experience, although I can do the basics, and had never made a crocheted item with more than one piece before. To make things more confusing, the only direction re joining the squares was this:
"Sew squares together using a tapestry needle and color A, matching edges, and working stitch to stitch."
OK, very well, but sew together how?
After thinking about it, I decided to use good old mattress stitch. I like mattress stitch and I wanted at least one side of the blanket to not show any seaming. So, there are small seams on the wrong side of the blanket, but they are fairly innocuous, and I get the nice flush side-to-side look on the right side.
A final issue that I will probably have to deal with as I finish this is that the Shibui, while similar to the Koigu, crocheted at a very slightly larger gauge. This is causing a little bit of rippling, but it seems to be evening out as I join the strips. As anal as I am, I wasn't concerned enough about it to block all the little squares before joining them. This is supposed to be my Happy Project!!