Casting on new project

I finished my cousin's baby blanket. It is beautiful and soft and I love it. I bought yarn to start another blanket, but haven't been able to cast on yet. The wonderful box that my husband made for the yarn (so it doesn't tangle) was a bit to small, so he is going to fix it. He hasn't had the time though, so I'm without a box. I don't want to start the blanket for fear of the yarn getting super tangled like it did previously. So, I have the scarf that I can knit, but don't really feel like knitting that right now. Therefore, I think I'm going to start a hat project. I am going to use the Basic Tam with Flowers pattern from my One-Skein Wonders book. Now to decide which yarn to use...