For this blanket, I used Hayfield Bonus DK wool; simply because it's a cheap acrylic available at a local wool shop: ten 100g balls for 12 pounds is hard to beat; particularly when you're on maternity leave. It's not as nice to feel as the lovely Debbie Bliss that I would normally use; and quite splitty; but it's sturdy, and not as difficult to crochet with as I would have imagined. I was going to block the squares, but I decided it probably wasn't worth the effort - I think in retrospect, I would the next time.
I'm very chuffed with it - as is my three year old, who has used it for picnics for him and the toys and a tent already. I hope it's up to the task ahead. In the meantime, I'm carefully considering a next project as my other two are slightly boring me. I'm still in love with granny squares, and am considering making even more big granny square blankets as gifts for a couple of girls I know. We'll see.