I play with a group of very experienced players. Many have been playing if not DMing themselves for over 20 years. I find if I set any standard monster on the table They know what they are facing and are not bothered by it at all. So lately I have taken to slightly modifying, in many cases only so much as appearance monsters before introducing them in the fight.
For example I am currently playing a city compaign and rather then having my party face kobolds, knowing full well what a kobold is I describe a small stature, anthropomorphic racoon.
I am currently working on the idea of Aldrick the Mad's **** Talking Mushroom. Aldrick was an eccentric old wizard who in his old age went rather mad. After several encounters with Shriekers he decided he needed to know what they were trying to say. So after several years of experimenting on them he gave them the power of telepathy and as a result anyone who could hear its shriek now also gets bombarded with inappropriate, telepathic messages about their mother or in the case of the priest their inability to jump. Think psych out from Baseketball if you ever saw it.