Have you tried Rambouillet yet?  We love this bouncy fiber!  Soka'pii is a single-ply with a nice high twist.  Rustically sheepy but with a soft, spongey hand.

From The Farmer's Daughter Fibers:

"Soka’pii (pronounced Sue-copy) is the Blackfeet word for ‘good’. A unique single-ply fingering weight yarn, this Montana and Wyoming raised Rambouillet is bouncy with a cozy composition.

A subtle thick and thin character will give your garments a delightful texture, as well as give you an interesting knitting experience."