Although it has warmed up here considerably (+20 yesterday!) we're still in our long johns everyday. We keep the thermostat low (62ish) and head out into the snow each day. Lupine's cashmere long johns have been a huge hit, so I finished stitching up a coordinating shirt for her as well.
I used a long sleeve t-shirt pattern that I had on hand as the springboard for my pattern. (From Ottobre winter 2004, if you want specifics.) I used the existing sweater sleeves but narrowed and shortened them from the shoulder and also used a portion of the existing neck hole to avoid having to add ribbing that I didn't have on hand. The neck was a bit too small so I added a notch at the manufactured seam to make it go on easily.
Because Lupine wears dresses almost every day I left the shirt extra long (to keep her extra warm), and decided to make the sleeves cuffed. My theory is that next winter with the extra length in the body and arms it will still fit. Soft, warm, and woolly. $1.50 and fifteen minutes. Works for me.
Hooray for homemade!