The silk long johns from terramar etc dont compare to the european wool silk blends by ruskovilla, engel or hocosa. Ruskovilla makes a 100% silk long johns which are like a silk jersey and are very durable. Expensive though, but great for very sensitive skin. Engel makes fun stripes and colors in the wool silk too. The wool silk is super soft and my entire family wears it. We get ours from my friend Michelle at Green Mountain Organics, she imports ruskovilla and engel.
I love my silk/wool long johns, and yes, they are $$$, but I am hoping they last. I got mine from Nordic Woolens and ordered XL, but should have ordered L. If anyone out there wants a pair or worn-once long johns, I'll ship them to you for free for $10 less than they are online before shipping. I'd rather have a snug fit.
I also loved my Smart Wool long johns which were I think almost 100% wool, but they tore after one season of heavy bike commuting and near daily wear. I contacted customer care and got a replacement set!