Silky Wool is the nicest wool in the world to wear next to the skin. It provides warmth, but not insufferable heat. I mean, it doesn't suffocate. So worn under my Bettna, I'll be very comfortable!
Noro's "Maiko" has the same attributes as Silky Wool. A tad warmer though. And less colors to chose from. And more expensive.
You can pick up Silky Wool for a great price. And it has nearly 200 yards per hank. Very generous yardage IMO.