the koigu looks gorgeous, but I don't enjoy knitting with it (the "hand" is too dry for me). It's doubled, so basicallly you're looking for a light worsted. If you don't double, you only use four skeins instead of eight.
I love knitting with Lorna's Laces Shepherd's Worsted, and also Mountain Colours' 4/8 worsted (which is what this baby blanket will be, if i ever get off my ass long enough to knit it). I like variegated wools for this pattern because it's VERY simple (I think boring, in some ways) and the yarn really shows off.