A good read from King Arthur- Choosing the Best Type (of Yeast) for Any Recipe.

Their pick has been my favorite for years- SAF instant yeast. I buy a 1lb bag of this, and replace it every 6 months. KA has a nice little set which includes the yeast, as well as a container for it (which I also use). Put that in your fridge and you'll be set for a long while.