Gotta agree with Lenard as Sarek. Playing a man with emotions just below the surface. It also helps that he's the first full Vulcan we saw.
I also liked Townes in "Archons", however and would recommend his performance in a two-parter episode of "The Incredible Hulk" called "The First", in which he plays a man who was hulkified 30 years before Banner, cured, and wants the power back.
I remember Townes in "The First". Amazing performance. He starts out as this little nebbish, but once he regains the power, it becomes all too obvious why the man that gave it to him took it away. He was Evil. Not just evil, but Evil.