Dibs. Everyone saw me say it.
It may just be me, but every time I have had a pair of gray pants that were not wool I never wore them/never looked quite right. For me linen and cotton are best in tan/cream.
If u think there's a possibility that you'll be sensitive, then to the knee is a good idea, although the scratchiness ime is more from thread ends exposed along the over-locking at the seams, and the lining doesn't protect u from that.