If you've spent any time on Ravelry, you might have noticed the yarn "Cascade 220" is usually at the top of the popularity list on the yarns page. (Why "220"? I'm guessing it's because each skein has 220 yards! )
Cascade 220 is a real workhorse. Nice fat 100g skeins of worsted weight yarn, with great yardage, 100% Peruvian highland wool, and over 150 colours to choose from in the solids and heathers, and almost the same selection again in the Cascade 220 Superwash. And there are specialty Cascade 220 yarns as well: Tweed, Paint and Quatro.
Versatile and affordable, Cascade 220 is a good option for the beginner knitter too. It's easy to work with, has good stitch definition, and is forgiving.
Some places you'll see Cascade 220:
There are many patterns out there for Cascade 220, but I want to link to one of my favorite man-patterns, Émilien, by the lovely Ariane of Falling Stitches. What can I say, I have a weakness for stripes. Now if I could just get Charles to wear them...
And, of course Cascade Yarns is much more than their 220. They have a huge selection of yarn, check out the pages for these:
Ultra Pima 100% Cotton
Cash Vero 12% Cashmere (what else is in it? who cares, you had me at Cashmere)
Pastaza 50% Llama 50% Wool
Sierra 80% Cotton 20% Wool
Venezia 70% Merino 30% Silk
Luna 100% Cotton
Greenland 100% Superwash Merino